Question

\(\left(1+x\right)^3+\left(1-x\right)^3=6\left(x+1\right)^2\)

Giải pt

Answer 1

\(\Leftrightarrow1+3x+3x^2+x^3+1-3x+3x^2-x^3=6\left(x+1\right)^2\)

\(\Leftrightarrow6x^2+2=6\left(x^2+2x+1\right)\)

\(\Leftrightarrow6x^2+2=6x^2+12x+6\)

\(\Leftrightarrow12x=-4\)

\(\Leftrightarrow x=-\dfrac{1}{3}\)

Answer 2

1+3x+3x²+1+1-3x²+3x-1=6(x²+2x+1)

6x² +2 = 6x²+12x+6

-12x - 4 = 0

=> x = 3