Question

What is the value of x

4x^3+3=867

Answer 1

minus 867 from both sides
4x³-864=0
undistribute 4
4(x³-216)=0
factor differnce of 2 perfect cubes
remember that a³-b³=(a-b)(a²+ab+b²)
so
(4)(x³-6³)=(4)(x-6)(x²+6x+36)=0
set each to 0

x-6=0
x=6

x²-6x+36=0
no real numbers will work for x

x=6

Answer 2

Isolate the x:

4x^3 = 864,

x^3 = 216

x = 6