Question

Tìm x, biết:

a. (7x - 11)³ = 2⁵ . 5² + 200

B.  3 với 1/3x + 16 với 3/4 = -13,25

Answer 1

a) (7x - 11)³ = 2⁵.5² + 200

(7x - 11)³ = 32.25 + 200

(7x - 11)³ = 800 + 200

(7x - 11)³ = 1000 = 10³

=> 7x - 11 = 10

=> 7x = 10 + 11 = 21

=> x = 21 : 7 = 3

b) \(1\frac{1}{3}x+16\frac{3}{4}=-13,25\)

=> \(\frac{4}{3}x+\frac{67}{4}=-\frac{53}{4}\)

=> \(\frac{4}{3}x=-\frac{53}{4}-\frac{67}{4}\)

=> \(\frac{4}{3}x=-30\)

=> \(x=-30:\frac{4}{3}\)

=> \(x=-30.\frac{3}{4}=-\frac{45}{2}\)