Question

Tìm x thuộc Z biết

A)     (x + 3 )² =49

B)     7x + 10 =5x-2

Answer 1

a. (x+3)²=49

=> (x+3)²=7²=(-7)²

=> x+3=7           hoặc x+3=-7

=> x=7-3            hoặc x=-7-3

=> x=4               hoặc x=-10

b. 7x+10=5x-2

=> 7x-5x=-2-10

=> 2x=-12

=> x=-12:2

=> x=-6

Answer 2

a) (x+3) ² = 49                        b)7x+10=5x-2

(x+3) ²  = 7²                                        5x-7x=10+2

=>x+3=7                                         -2x= 12

=>x=4                                         =>x= -6