Đáp án:
$a)
x=\dfrac{1}{3}\\
b)
x=1\\
c)
x=2\\
d)
x=12$
Giải thích các bước giải:
$a)
(x+1)^3-x^2(x+3)=2\\
\Leftrightarrow x^3+3x^2+3x+1-x^3-3x^2-2=0\\
\Leftrightarrow 3x-1=0\\
\Leftrightarrow 3x=1\\
\Leftrightarrow x=\dfrac{1}{3}\\
b)
(x-2)^3-x(x+1)(x-1)+6x^2=5\\
\Leftrightarrow x^3-6x^2+12x-8-x(x^2-1)+6x^2=5\\
\Leftrightarrow x^3-6x^2+12x-8-x^3+x+6x^2=5\\
\Leftrightarrow 13x=13\\
\Leftrightarrow x=1\\
c)
(x-3)(x^2+3x+9)-x(x-4)(x+4)=5\\
\Leftrightarrow x^3-27-x(x^2-16)=5\\
\Leftrightarrow x^3-27-x^3+16x=5\\
\Leftrightarrow 16x=32\\
\Leftrightarrow x=2\\
d)
(x-2)^3-(x+5)(x^2-5x+25)+6x^2=11\\
\Leftrightarrow x^3-6x^2+12x-8-(x^3+125)+6x^2=11\\
\Leftrightarrow x^3-6x^2+12x-8-x^3-125+6x^2=11\\
\Leftrightarrow 12x=144\\
\Leftrightarrow x=12$
