Câu hỏi của Lê Chi Mai

Question

Bài 9: Tìm x, biết: a) (x-3)^2=1;  b)  ( x - 1/ 7 )^2 =0 ;  c) ( 2x +3)^3= -27; d) ( 2+1/2)^2 =1/4 .x; e) -(5+35.x)^2=36

Mong các bạn giúp đỡ mình nhé! Mình cảm ơn!

✿✿❑ĐạT̐®ŋɢย❐✿✿ · Accepted Answer

a) $\left(x-3\right)^2=1$

$\Leftrightarrow x-3=1$

$\Leftrightarrow x=4$

b) $\left(x-\frac{1}{7}\right)^2=0$

$\Leftrightarrow x-\frac{1}{7}=0$

$\Leftrightarrow x=\frac{1}{7}$

c) $\left(2x+3\right)^3=-27=\left(-3\right)^3$

$\Leftrightarrow2x+3=-3$

$\Leftrightarrow2x=-6$

$\Leftrightarrow x=-3$

d) $\left(2+\frac{1}{2}\right)^2=\frac{1}{4}.x$

$\Leftrightarrow\frac{25}{4}=\frac{1}{4}.x$

$\Leftrightarrow x=\frac{25}{4}:\frac{1}{4}$

$\Leftrightarrow x=25$

e) $-\left(5+35.x\right)^2=36=6^2$

$\Leftrightarrow-\left(5+35.x\right)=6$

$\Leftrightarrow5+35.x=-6$

$\Leftrightarrow35.x=-6-5=-11$

$\Leftrightarrow x=-\frac{11}{35}$

Đúng không ta ???Câu trả lời: a) $\left(x-3\right)^2=1$