Question

a. 7-4(x+1)=3x-5

c.\(\dfrac{5x+8}{3}=\dfrac{4-2x}{4}\)       d. (9x-1)²=5

Answer 1

Lời giải:

a. $7-4(x+1)=3x-5$
$7-4x-4=3x-5$

$3-4x=3x-5$

$3+5=3x+4x$

$8=7x$

$x=\frac{8}{7}$

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c.

$\frac{5x+8}{3}=\frac{4-2x}{4}$

$\Rightarrow 4(5x+8)=3(4-2x)$

$\Rightarrow 20x+32=12-6x$

$\Rightarrow 20x+6x=12-32$

$\Rightarrow 26x=-20$

$\Rightarrow x=\frac{-20}{26}=\frac{-10}{13}$

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d. 

$(9x-1)^2=5=(\sqrt{5})^2=(-\sqrt{5})^2$

$\Rightarrow 9x-1=\sqrt{5}$ hoặc $9x-1=-\sqrt{5}$

$\Rightarrow x=\frac{\sqrt{5}+1}{9}$ hoặc $x=\frac{1-\sqrt{5}}{9}$