Question

Tìm x, biết :

a.(x+ 5)3 = - 64

b.(2x- 3)2 = 9

Answer 1

a.(x + 5) . 3 = - 64

=> x + 5 = -64 : 3

=> x + 5 = \(-\frac{64}{3}\)

=> x = \(-\frac{64}{3}\) - 5

=> x = \(-\frac{64}{3}\) - \(\frac{15}{3}\)

=> x = \(-\frac{79}{3}\)

b.(2x - 3) . 2 = 9

=> 2x - 3 = 9 : 2

=> 2x - 3 = \(\frac{9}{2}\)

=> 2x = \(\frac{9}{2}\) +3

=> 2x = \(\frac{15}{2}\)

=> x = \(\frac{15}{2}\) : 2

=> x = \(\frac{15}{2}\) . \(\frac{1}{2}\)

=> x = \(\frac{15}{4}\)

HỌC TỐT

Answer 2

a.(x+5)3=-64

x+5=-64:3

x+5=\(\frac{-64}{3}\)

x=\(\frac{-64}{3}-5\)

x=\(\frac{-64}{3}-\frac{15}{3}\)

x=\(\frac{-79}{3}=-26\frac{1}{3}\)

b.(2x-3)2=9

2x-3=9:2

2x-3=\(\frac{9}{2}\)

2x=\(\frac{9}{2}+3\)
2x=\(\frac{15}{2}\)
x=\(\frac{15}{2}:2\)
x=\(\frac{15}{4}\)=\(3\frac{3}{4}\)