LATIHAN SOAL
Soal 01
Tentukan bentuk sederhana dari:
A. \(3^{15} + 3^{15} + 3^{15}\)
B. \(2^{25} + 2^{25} + 2^{25} + 2^{25}\)
Pembahasan
A. \(3^{15} + 3^{15} + 3^{15}\)
\begin{equation*}
\begin{split}
& 3^{15} + 3^{15} + 3^{15} \\\\
& 3 \:.\: 3^{15} \\\\
& \bbox[5px, border: 2px solid magenta] {3^{16}}
\end{split}
\end{equation*}
B. \(2^{25} + 2^{25} + 2^{25} + 2^{25}\)
\begin{equation*}
\begin{split}
& 2^{25} + 2^{25} + 2^{25} + 2^{25} \\\\
& 4 \:.\: 2^{25} \\\\
& 2^2 \:.\: 2^{25} \\\\
& \bbox[5px, border: 2px solid magenta] {2^{27}}
\end{split}
\end{equation*}
Soal 02
Sederhanakan bentuk eksponen di bawah ini dalam bentuk pangkat positif:
A. \(\dfrac{a^4}{a^3 \:.\: b^2} \times \dfrac{a^7 \:.\: b^3}{a \:.\: b^6}\)
B. \(\left(\dfrac{x^5 \:.\: y}{x^3 \:.\: y^4}\right)^4 \div \left(\dfrac{x^4}{x \:.\: y^2}\right)^6\)
Pembahasan
A. \(\dfrac{a^4}{a^3 \:.\: b^2} \times \dfrac{a^7 \:.\: b^3}{a \:.\: b^6}\)
\begin{equation*}
\begin{split}
& \frac{a^4}{a^3 \:.\: b^2} \times \frac{a^7 \:.\: b^3}{a \:.\: b^6} \\\\
& \frac{a^4 \:.\: a^7}{a^3 \:.\: a} \times \frac{b^3}{b^2 \:.\: b^6} \\\\
& \frac{a^{11}}{a^4} \times \frac{b^3}{b^8} \\\\
& \frac{a^7}{1} \times \frac{1}{b^5} \\\\
& \bbox[5px, border: 2px solid magenta] {\frac{a^7}{b^5}}
\end{split}
\end{equation*}
B. \(\left(\dfrac{x^5 \:.\: y}{x^3 \:.\: y^4}\right)^4 \div \left(\dfrac{x^4}{x \:.\: y^2}\right)^6\)
\begin{equation*}
\begin{split}
& \left(\frac{x^5 \:.\: y}{x^3 \:.\: y^4}\right)^4 \div \left(\frac{x^4}{x \:.\: y^2}\right)^6 \\\\
& \left(\frac{x^2}{y^3}\right)^4 \div \left(\frac{x^3}{y^2}\right)^6 \\\\
& \frac{x^8}{y^{12}} \div \frac{x^{18}}{y^{12}} \\\\
& \frac{x^8}{y^{12}} \times \frac{y^{12}}{x^{18}} \\\\
& \bbox[5px, border: 2px solid magenta] {\frac{1}{x^{10}}}
\end{split}
\end{equation*}
Soal 03
Nyatakan bentuk eksponen di bawah ini menjadi bentuk akar:
\begin{equation*}
\frac{(x^{\frac{2}{3}} \:.\: y^{\frac{2}{3}})^{-2}}{(x^{\frac{1}{2}} \:.\: y^{\frac{1}{4}})^{-3}}
\end{equation*}
Pembahasan
\begin{equation*}
\begin{split}
& \frac{(x^{\frac{2}{3}} \:.\: y^{\frac{2}{3}})^{-2}}{(x^{\frac{1}{2}} \:.\: y^{\frac{1}{4}})^{-3}} \\\\
& \frac{x^{-\frac{4}{3}} \:.\: y^{-\frac{4}{3}}}{x^{-\frac{3}{2}} \:.\: y^{-\frac{3}{4}}} \\\\
& x^{-\frac{4}{3} + \frac{3}{2}} \:.\: y^{-\frac{4}{3} + \frac{3}{4}} \\\\
& x^{\frac16} \:.\: y^{-\frac{7}{12}} \\\\
& \frac{x^{\frac{1}{6}}}{y^{\frac{7}{12}}} \\\\
& \bbox[5px, border: 2px solid magenta] {\frac{\sqrt [6] {x}}{\sqrt [12] {y^7}}}
\end{split}
\end{equation*}
Soal 04
Sederhanakan bentuk di bawah ini:
A. \(\dfrac{x \:.\: y^{-1} - y \:.\: x^{-1}}{x^{-1} + y^{-1}}\)
B. \(\dfrac{a \:.\: b^{-2} + a^{-2} \:.\: b}{a^{-2} - b^{-2}}\)
Pembahasan
A. \(\dfrac{x \:.\: y^{-1} - y \:.\: x^{-1}}{x^{-1} + y^{-1}}\)
\begin{equation*}
\begin{split}
& \frac{x \:.\: y^{-1} - y \:.\: x^{-1}}{x^{-1} + y^{-1}} \\\\
& \frac{\dfrac{x}{y} - \dfrac{y}{x}}{\dfrac{1}{x} + \dfrac{1}{y}} \quad {\color {blue} \times \: \frac{xy}{xy}} \\\\
& \frac{x^2 - y^2}{y + x} \\\\
& \frac{\cancel{(x + y)}(x - y)}{\cancel{y + x}} \\\\
& \bbox[5px, border: 2px solid magenta] {x - y}
\end{split}
\end{equation*}
B. \(\dfrac{a \:.\: b^{-2} + a^{-2} \:.\: b}{a^{-2} - b^{-2}}\)
\begin{equation*}
\begin{split}
& \frac{a \:.\: b^{-2} + a^{-2} \:.\: b}{a^{-2} - b^{-2}} \\\\
& \frac{\dfrac{a}{b^2} + \dfrac{b}{a^2}}{\dfrac{1}{a^2} - \dfrac{1}{b^2}} \quad {\color {blue} \times \: \frac{a^2 \: b^2}{a^2 \: b^2}} \\\\
& \frac{a^3 + b^3}{b^2 - a^2} \\\\
& \frac{\cancel{(a + b)}(a^2 + ab + b^2)}{\cancel{(b + a)}(b - a)} \\\\
& \bbox[5px, border: 2px solid magenta] {\frac{a^2 + ab + b^2}{b - a}}
\end{split}
\end{equation*}
Soal 05
Sederhanakan bentuk di bawah ini:
A. \(\dfrac{3^{n + 1} + 3^n}{3^{n + 2} + 3^{n - 1}}\)
B. \(\dfrac{(x^{a + 1})^b \:.\: x^{a + b}}{x^{a(b + 1)} \:.\: x^{2b}}\)
Pembahasan
A. \(\dfrac{3^{n + 1} + 3^n}{3^{n + 2} + 3^{n - 1}}\)
\begin{equation*}
\begin{split}
& \frac{3^{n + 1} + 3^n}{3^{n + 2} + 3^{n - 1}} \\\\
& \frac{3^n \:.\: 3 + 3^n}{3^n \:.\: 3^2 + 3^n \:.\: 3^{- 1}} \\\\
& \frac{ \cancel{3^n} \:.\: (3 + 1)}{\cancel{3^n} \:.\: (3^2 + 3^{- 1})} \\\\
& \frac{4}{9 + \frac{1}{3}} \quad {\color {blue} \times \: \frac{3}{3}} \\\\
& \frac{12}{27 + 1} \\\\
& \frac{12}{28} \\\\
& \bbox[5px, border: 2px solid magenta] {\frac{3}{7}}
\end{split}
\end{equation*}
B. \(\dfrac{(x^{a + 1})^b \:.\: x^{a + b}}{x^{a(b + 1)} \:.\: x^{2b}}\)
\begin{equation*}
\begin{split}
& \frac{(x^{a + 1})^b \:.\: x^{a + b}}{x^{a(b + 1)} \:.\: x^{2b}} \\\\
& \frac{x^{ab} \:.\: x^b \:.\: x^a \:.\: x^b}{x^{ab} \:.\: x^a \:.\: x^{2b}} \\\\
& \frac{x^{ab} \:.\: x^a \:.\: x^{2b}}{x^{ab} \:.\: x^a \:.\: x^{2b}} \\\\
& \bbox[5px, border: 2px solid magenta] {1}
\end{split}
\end{equation*}
Soal 06
Tentukan nilai eksak dari:
\begin{equation*}
\dfrac{\left(\dfrac{2}{5}\right)^{-2} \:.\: (32)^{\frac{3}{5}} - \left(\dfrac{1}{8}\right)^{-\frac{4}{3}}}{\left(\dfrac{8}{125}\right)^{-\frac{1}{3}} \cdot \left(\dfrac{9}{4}\right)^{-\frac{1}{2}} \:.\: (27)^{\frac{2}{3}} + \left(\dfrac{1}{3}\right)^{-2}}
\end{equation*}
Pembahasan
\begin{equation*}
\begin{split}
& \frac{\left(\dfrac{2}{5}\right)^{-2} \:.\: (32)^{\frac{3}{5}} - \left(\dfrac{1}{8}\right)^{-\frac{4}{3}}}{\left(\dfrac{8}{125}\right)^{-\frac{1}{3}} \:.\: \left(\dfrac{9}{4}\right)^{-\frac{1}{2}} \:.\: (27)^{\frac{2}{3}} + \left(\dfrac{1}{3}\right)^{-2}} \\\\
& \frac{\left(\dfrac{5}{2}\right)^{2} \:.\: (2^5)^{\frac{3}{5}} - \left(2^{-3}\right)^{-\frac{4}{3}}}{\left(\dfrac{5^3}{2^3}\right)^{\frac{1}{3}} \:.\: \left(\dfrac{2^2}{3^2}\right)^{\frac{1}{2}} \:.\: (3^3)^{\frac{2}{3}} + \left(3^{-1}\right)^{-2}} \\\\
& \frac{\dfrac{25}{4} \:.\: 2^3 - 2^4}{\dfrac{5}{2} \:.\: \dfrac{2}{3} \:.\: 3^2 + 3^2} \\\\
& \frac{50 - 16}{15 + 9} \\\\
& \frac{34}{24} \\\\
& \bbox[5px, border: 2px solid magenta] {\frac{17}{12}}
\end{split}
\end{equation*}
Soal 07
Tentukan nilai eksak dari:
\(\dfrac{(0,25)^{-\frac{1}{2}} \:.\: (0,125)^{-\frac{2}{3}} + (0,2)^{-2}}{(0,5)^{-2} + (0,2)^{-1} + 0,375 + (0,25)^0}\)
Pembahasan
\begin{equation*}
\begin{split}
& \frac{(0,25)^{-\frac{1}{2}} \:.\: (0,125)^{-\frac{2}{3}} + (0,2)^{-2}}{(0,5)^{-2} + (0,2)^{-1} + 0,375 + (0,25)^0} \\\\
& \frac{\left(\dfrac{1}{4}\right)^{-\frac{1}{2}} \:.\: \left(\dfrac{1}{8}\right)^{-\frac{2}{3}} + \left(\dfrac{1}{5}\right)^{-2}}{\left(\dfrac{1}{2}\right)^{-2} + \left(\dfrac{1}{5}\right)^{-1} + \dfrac{3}{8} + 1} \\\\
& \frac{(2^{-2})^{-\frac{1}{2}} \cdot (2^{-3})^{-\frac{2}{3}} + (5^{-1})^{-2}}{(2^{-1})^{-2} + (5^{-1})^{-1} + \dfrac{3}{8} + 1} \\\\
& \frac{2 \:.\: 4 + 25}{4 + 5 + \dfrac{3}{8} + 1} \\\\
& \frac{33}{10 + \dfrac{3}{8}} \quad {\color {blue} \times \: \frac{8}{8}} \\\\
& \frac{264}{80 + 3} \\\\
& \bbox[5px, border: 2px solid magenta] {\frac{264}{83}}
\end{split}
\end{equation*}
Soal 08
Tentukan nilai eksak dari:
\(\dfrac{(0,111\dotso)^{2} + (6,25)^{\frac{1}{2}}}{(0,555\dotso)^2 + (2,25)^{\frac{1}{2}}}\)
Pembahasan
\begin{equation*}
\begin{split}
& \frac{(0,111\dotso)^{2} + (6,25)^{\frac{1}{2}}}{(0,555\dotso)^2 + (2,25)^{\frac{1}{2}}} \\\\
& \frac{\left(\dfrac{1}{9}\right)^{2} + \left(6 \dfrac{1}{4}\right)^{\frac{1}{2}}}{\left(\dfrac{5}{9}\right)^2 + \left(2 \dfrac{1}{4}\right)^{\frac{1}{2}}} \\\\
& \frac{\left(\dfrac{1}{9}\right)^{2} + \left(\dfrac{25}{4}\right)^{\frac{1}{2}}}{\left(\dfrac{5}{9}\right)^2 + \left(\dfrac{9}{4}\right)^{\frac{1}{2}}} \\\\
& \frac{\dfrac{1}{81} + \dfrac{5}{2}}{\dfrac{25}{81} + \dfrac{3}{2}} \quad {\color {blue} \times \: \frac{81 \:.\: 2}{81 \:.\: 2}} \\\\
& \frac{2 + 405}{50 + 243} \\\\
& \bbox[5px, border: 2px solid magenta] {\frac{407}{293}}
\end{split}
\end{equation*}
Soal 09
Tentukan nilai \(a\), \(b\) dan \(c\) dari
\begin{equation*}
\frac{60^8 \:.\: 45^7 \:.\: 72^6}{50^6 \:.\: 48^7 \:.\: 75^8} = 2^a \:.\: 3^b \:.\: 5^c
\end{equation*}
Pembahasan
\begin{equation*}
\begin{split}
& \frac{60^8 \:.\: 45^7 \:.\: 72^6}{50^6 \:.\: 48^7 \:.\: 75^8} \\\\
& \frac{(2^2 \:.\: 3 \:.\: 5)^8 \:.\: (3^2 \:.\: 5)^7 \:.\: (2^3 \:.\: 3^2)^6}{(2 \:.\: 5^2)^6 \:.\: (2^4 \:.\: 3)^7 \:.\: (3 \:.\: 5^2)^8} \\\\
& \frac{2^{16} \:.\: 3^8 \:.\: 5^8 \:.\: 3^{14} \:.\: 5^7 \:.\: 2^{18} \:.\: 3^{12}}{2^6 \:.\: 5^{12} \:.\: 2^{28} \:.\: 3^7 \:.\: 3^8 \:.\: 5^{16}} \\
\end{split}
\end{equation*}
\begin{equation*}
2^{16 + 18 - 6 - 28} \:.\: 3^{8 + 14 + 12 - 7 - 8} \:.\: 5^{8 + 7 -12 - 16} \\
\end{equation*}
\begin{equation*}
2^{0} \:.\: 3^{19} \:.\: 5^{-13} \\
\end{equation*}
a = 0, b = 19 dan c = −13
Soal 10
Urutkan bilangan di bawah ini dari yang terkecil:
(A) \(25^{600}, \quad 81^{400}, \quad 256^{300}\)
(B) \(2^{\frac 12}, \quad 3^{\frac 14}, \quad 5^{\frac 16}, \quad 10^{\frac {1}{12}}\)
Pembahasan
(A) \(25^{600}, \quad 81^{400}, \quad 256^{300}\)
\begin{equation*}
\begin{split}
25^{600} & = (5^2)^{600} = 5^{1200} = (5^{3})^{400} = (125)^{400} \quad {\color {blue} \dotso \: (3)}\\\\
81^{400} & = (3^4)^{400} = 3^{1600} = (3^{4})^{400} = (81)^{400} \quad {\color {blue} \dotso \: (2)} \\\\
256^{300} & = (2^8)^{300} = 2^{2400} = (2^{6})^{400} = (64)^{400} \quad {\color {blue} \dotso \: (1)}
\end{split}
\end{equation*}
\(256^{300} <81^{400} < 25^{600} \)
Soal 11
Jika \(3^x + 3^{-x} = 5\), tentukan nilai dari:
A. \(9^{x} + 9^{-x}\)
B. \(27^{x} + 27^{-x}\)
Pembahasan
A. \(9^{x} + 9^{-x}\)
\begin{equation*}
\begin{split}
& 3^x + 3^{-x} = 5 \quad {\color {blue} \text{(kuadratkan kedua ruas)}}\\\\
& \left(3^x + 3^{-x}\right)^2 = 25 \\\\
& \left(3^x \right)^2 + 2 \:.\: 3^x \:.\: 3^{-x} + \left(3^{-x}\right)^2 = 25 \\\\
& 3^{2x} + 2 \:.\: 3^0 + 3^{-2x} = 25 \\\\
& 3^{2x} + 2 \:.\: 1 + 3^{-2x} = 25 \\\\
& 3^{2x} + 3^{-2x} = \bbox[5px, border: 2px solid magenta] {23}
\end{split}
\end{equation*}
Soal 12
A. Jika \(2^{2x} + 2^{-2x} = 23\), tentukan nilai dari \(2^{3x} + 2^{-3x}\)
B. Jika \(x^{2} + \dfrac {1}{x^2} = 14\), tentukan nilai dari \(x^{3} + \dfrac {1}{x^3}\)
Pembahasan
A. Jika \(2^{2x} + 2^{-2x} = 47\), tentukan nilai dari \(2^{3x} + 2^{-3x}\)
\begin{equation*}
\begin{split}
& \left(2^x + 2^{-x}\right)^2 = \left(2^x \right)^2 + 2 \:.\: 2^x \:.\: 2^{-x} + \left(2^{-x} \right)^2 \\\\
& \left(2^x + 2^{-x}\right)^2 = 2^{2x} + 2 \:.\: 2^0 + 2^{-2x} \\\\
& \left(2^x + 2^{-x}\right)^2 = 47 + 2 \\\\
& \left(2^x + 2^{-x}\right)^2 = 49 \\\\
& 2^x + 2^{-x} = 7
\end{split}
\end{equation*}
\begin{equation*}
\begin{split}
& 2^x + 2^{-x} = 7 \quad {\color {blue} \text{(pangkat tiga kedua ruas)}}\\\\
& \left(2^x + 2^{-x}\right)^3 = 343 \\\\
& \left(2^x \right)^3 + 3 \:.\: \left(2^x \right)^2 \:.\: 2^{-x} + 3 \:.\: 2^x \:.\: \left( 2^{-x} \right)^2 + \left(2^{-x}\right)^3 = 343 \\\\
& 2^{3x} + 3 \:.\: 2^{2x} \:.\: 2^{-x} + 3 \:.\: 2^x \:.\: 2^{-2x} + 2^{-3x} = 343 \\\\
& 2^{3x} + 3 \:.\: 2^{x} + 3 \:.\: 2^{-x} + 2^{-3x} = 343 \\\\
& 2^{3x} + 3 \left( 2^{x} + 2^{-x} \right) + 2^{-3x} = 343 \\\\
& 2^{3x} + 3 \:.\: 7 + 2^{-3x} = 343 \\\\
& 2^{3x} + 21 + 2^{-3x} = 343 \\\\
& 2^{3x} + 2^{-3x} = \bbox[5px, border: 2px solid magenta] {322}
\end{split}
\end{equation*}
B. Jika \(x^{2} + \dfrac {1}{x^2} = 14\), tentukan nilai dari \(x^{3} + \dfrac {1}{x^3}\)
\begin{equation*}
\begin{split}
& \left(x + \frac 1x \right)^2 = x^2 + 2 \:.\: x \:.\: \frac 1x + \left(\frac 1x \right)^2 \\\\
& \left(x + \frac 1x \right)^2 = x^2 + 2 + \frac {1}{x^2} \\\\
& \left(x + \frac 1x \right)^2 = 14 + 2 \\\\
& \left(x + \frac 1x \right)^2 = 16 \\\\
& x + \frac 1x = 4
\end{split}
\end{equation*}
\begin{equation*}
\begin{split}
& x + \frac 1x = 4 \quad {\color {blue} \text{(pangkat tiga kedua ruas)}}\\\\
& x^3 + 3 \:.\: x^2 \:.\: \frac 1x + 3 \:.\: x \:.\: \left(\frac 1x \right)^2 + \left( \frac 1x \right)^3 = 64 \\\\
& x^3 + 3 \:.\: x + 3 \:.\: \frac 1x + \frac {1}{x^3} = 64 \\\\
& x^3 + 3 \left( x + \frac 1x \right) + \frac {1}{x^3} = 64 \\\\
& x^3 + 3 \:.\: 4 + \frac {1}{x^3} = 64 \\\\
& x^3 + 12 + \frac {1}{x^3} = 64 \\\\
& x^3 + \frac {1}{x^3} = \bbox[5px, border: 2px solid magenta] {52}
\end{split}
\end{equation*}
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