tìm x
a)12 . (x-2)=0
b) 3(mũ 2) + 5x = 7 mũ 2
c )-45 + x= -27
d ) ( x-47)-115=0
e) 2 mũ 4 . x – 3 mũ 2 .x= 145-5
g) 12x-333= 3 mũ 2 . 3 mũ 3
tìm x
a)12 . (x-2)=0
b) 3(mũ 2) + 5x = 7 mũ 2
c )-45 + x= -27
d ) ( x-47)-115=0
e) 2 mũ 4 . x – 3 mũ 2 .x= 145-5
g) 12x-333= 3 mũ 2 . 3 mũ 3
$\begin{array}{l}
a)\,\,12.\left( {x – 2} \right) = 0\\
\,\,\,\,\,\,\,\,x – 2 = 0\\
\,\,\,\,\,\,\,\,x = 0 + 2\\
\,\,\,\,\,\,\,x = 2\\
b)\,\,{3^2} + 5x = {7^2}\\
\,\,\,\,\,\,\,9 + 5x = 49\\
\,\,\,\,\,\,\,\,5x = 49 – 9\\
\,\,\,\,\,\,\,\,5x = 40\\
\,\,\,\,\,\,\,\,x = 40:5\\
\,\,\,\,\,\,\,\,x = 8\\
c)\,\, – 45 + x = – 27\\
\,\,\,\,\,\,\,\,x = – 27 – \left( { – 45} \right)\\
\,\,\,\,\,\,\,\,x = – 27 + 45\\
\,\,\,\,\,\,\,\,x = 18\\
d)\,\,\left( {x – 47} \right) – 115 = 0\\
\,\,\,\,\,\,\,\,x – 47 = 0 + 115\\
\,\,\,\,\,\,\,\,x – 47 = 115\\
\,\,\,\,\,\,\,\,x = 115 + 47\\
\,\,\,\,\,\,\,\,x = 162
\end{array}$
Hai câu còn lại em làm tương tự nhé.
Đáp án:
Hai câu cuối đây :
` e) 2^4.x – 3^2.x = 145 – 5`
` => x. (2^4 -3^2 ) = 140`
` => x . 7 = 140`
` => x= 20`
`g) 12x – 333 = 3^2.3^3`
` => 12x – 333 = 9.27`
` => 12x – 333 = 243`
` => 12x = 576`
` => x = 48`