Bài 1: Tìm x, biết: a, x : (-1/2) mũ 2= 1/2 b, (2/5) mũ 7 . x = (2/5) mũ 10 c, (3x – 2) mũ 5 = 0 d, (x – 1/3) mũ 2 = 35/36 e, (4x + 1) mũ 3 = -125 g,

a

x:$(\frac{-1}{2})^{2}$ =$\frac{1}{2}$

x:$\frac{1}{4}$= $\frac{1}{2}$

x=$\frac{1}{2}$ .$\frac{1}{4}$ x=$\frac{1}{8}$

b

$(\frac{2}{5})^{7}$.x=$(\frac{2}{5})^{10}$

x=$(\frac{2}{5})^{10}$:$(\frac{2}{5})^{7}$

x=$(\frac{2}{5})^{3}$

c

$(3x-2)^{5}$ =0

⇔3x-2=0

⇔3x=2 

⇔x=$\frac{2}{3}$

d

$(3x-\frac{1}{3})^{2}$=$\frac{25}{36}$ 

$(3x-\frac{1}{3})^{2}$=$(\frac{5}{6})^2$

$3x-\frac{1}{3}$=$\frac{5}{6}$ 

3x=$\frac{5}{6}$ + $\frac{1}{3}$

3x=$\frac{7}{6}$

x=$\frac{7}{18}$ 

e

$(5x+1)^{3}$=-125

$(5x+1)^{3}$= $(-5)^{3}$

5x+1=-5

5x=-6

x=$\frac{-6}{5}$ 

g,

$(5x+1)^{2}$ =$\frac{1}{25}$

$(5x+1)^{2}$ =$(\frac{1}{5})^2$

5x+1=0,2

5x=-0,8

x=0,16=$\frac{4}{25}$ 

Trả lời