Question

Tìm x \(\in\) N , biết :

(7x -11)³ = 2⁵ . 5² + 200

Answer 1

(7x - 11)³ = 2⁵ . 5² + 200

(7x - 11)³ = 32 . 25 + 200

(7x - 11)³ = 800 + 200

(7x - 11)³ = 1000

(7x - 11)³ = 10³ 

7x - 11 = 10

      7x  = 10 + 11

      7x  = 21

        x  = 21 : 7

        x = 3

Answer 2

=>(7x-11)^3=1000

=>\(\left(7x-11\right)^3=10^3\)

=>7x-11=10

=>7x=10+11

=>7x=21

=>x=21:7

=>x=3