TÌM X: a) x/4 = 9/x b) x-2/15 =-1/5

2 câu trả lời

a)

x4=9x

x.x=4.9

x2=36

x{±6}

 Vy x{±6}

b)

x-215=-15

x=-15+215

x=-115

 Vy x=-115

 

Đáp án:

a)

x4=9x

x.x=4.9

x2=36

x2=(±6)2

x=±6

Vậy x{6;-6}

b)

TH1:

x-215=-15

5.(x-2)=15.(-1)

5.(x-2)=-15

x-2=-3

x=-3+2

x=-1

Vậy x=-1

TH2 :

x-215=-15

x=-15+215

x=-315+215

x=115

Vậy x=115