a) 50 – [ 70 : ( x – 1 ) ] = 15
b) ( 5^2 + 2^3 ) . x + 4^2 = 7^2
c) 2 . x – 138 = 2^3 . 3^2
d) ( 2^6 – 4 . x ) . 8^39 = 2 . 8^40
e) 5 . ( x – 2 ) + 135 = 5^2 . 3^2
f) (
a) 50 – [ 70 : ( x – 1 ) ] = 15
b) ( 5^2 + 2^3 ) . x + 4^2 = 7^2
c) 2 . x – 138 = 2^3 . 3^2
d) ( 2^6 – 4 . x ) . 8^39 = 2 . 8^40
e) 5 . ( x – 2 ) + 135 = 5^2 . 3^2
f) (
Đáp án:
e) x=20
Giải thích các bước giải:
\(\begin{array}{l}
a)50 – \left[ {70:\left( {x – 1} \right)} \right] = 15\\
\to 70:\left( {x – 1} \right) = 35\\
\to x – 1 = 2\\
\to x = 3\\
b)({5^2} + {2^3}).x + {4^2} = {7^2}\\
\to \left( {25 + 8} \right)x + 16 = 49\\
\to 33x = 33\\
\to x = 1\\
c)2.x – 138 = {2^3}{.3^2}\\
\to 2x = 8.9 + 138\\
\to 2x = 210\\
\to x = 105\\
d)({2^6} – 4.x){.8^{39}} = {2.8^{40}}\\
\to 64 – 4x = 2.8\\
\to 4x = 48\\
\to x = 12\\
e)5.(x – 2) + 135 = {5^2}{.3^2}\\
\to 5\left( {x – 2} \right) = 25.9 – 135\\
\to 5\left( {x – 2} \right) = 90\\
\to x – 2 = 18\\
\to x = 20
\end{array}\)