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Question

a,3x+2  +   3x = 10

b,4 . 2x + 2x = 80

c, (x + 5 ) . ( x - 6) = 0

Nguyễn Thanh Hằng · Accepted Answer

a/ $3^{x+2}+3^x=10$

$\Leftrightarrow3^x.\left(3^2+1\right)=10$

$\Leftrightarrow3^x.10=10$

$\Leftrightarrow3^x=1$

$\Leftrightarrow3^x=3^0$

$\Leftrightarrow x=0$

Vậy...

b/ $4.2^x+2^x=80$

$\Leftrightarrow2^x\left(4+1\right)=80$

$\Leftrightarrow2^x.5=80$

$\Leftrightarrow2^x=16$

$\Leftrightarrow2^x=2^4$

$\Leftrightarrow x=4$

Vậy..

c/ $\left(x+5\right)\left(x-6\right)=0$

$\Leftrightarrow\left[{}\begin{matrix}x+5=0\x-6=0\end{matrix}\right.$

$\Leftrightarrow\left[{}\begin{matrix}x=-5\x=6\end{matrix}\right.$

Vậy..Câu trả lời: a/ $3^{x+2}+3^x=10$

$\Leftrightarrow3^x.\left(3^2+1\right)=10$

$\Leftrightarrow3^x.10=10$

$\Leftrightarrow3^x=1$

$\Leftrightarrow3^x=3^0$

$\Leftrightarrow x=0$

Vậy...

b/ $4.2^x+2^x=80$

$\Leftrightarrow2^x\left(4+1\right)=80$

$\Leftrightarrow2^x.5=80$

$\Leftrightarrow2^x=16$

$\Leftrightarrow2^x=2^4$

$\Leftrightarrow x=4$

Vậy..

c/ $\left(x+5\right)\left(x-6\right)=0$

$\Leftrightarrow\left[{}\begin{matrix}x+5=0\x-6=0\end{matrix}\right.$

$\Leftrightarrow\left[{}\begin{matrix}x=-5\x=6\end{matrix}\right.$

Vậy..

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