Tìm số nguyên x

a/x/4=9/x

b/x-2/15=-1/5

Đáp án+Giải thích các bước giải:

a,

`x/4=9/x`

`⇔x.x=9.4`

`⇔x^2=36`

`⇔x^2=(±6)^2`

`⇔x=±6`

Vậy `x=±6`

b,

`x-2/15=-1/5`

`⇔x=-1/5+2/15`

`⇔x=-3/15+2/15`

`⇔x=-1/15`

Vậy `x=-1/15`

$\text{@dieulinh2k7~~}$

$a)$

$\frac{x}{4}$ $=$$\frac{9}{x}$

$⇒$ $x.x$$=4.9$

$⇒$ $x^{2}$$=36$

$⇒$ $x^{2}$$=±6^{2}$

$⇒$ $x$$=±6$

$\text{Vậy $x∈${$6;-6$}}$

$b)$

$x-$$\frac{2}{15}$ $=$$\frac{-1}{5}$

$⇒$$x=$$\frac{-1}{5}+$$\frac{2}{15}$

$⇒$$x=$$\frac{-3}{15}+$$\frac{2}{15}$

$⇒$$x=$$\frac{-1}{15}$

$\text{Vậy $x=$$\frac{-1}{15}$ }$