(1+x²)^{2 _} 4x.(1- x²)

= (1+x^2) (1-x^2) - 4x (1-x^2)

= (1 + x^2 - 4x) (1- x^2)

= (x^2 - 4x +1) (1-x^2)

= (x-1)^2 (1-x) (1+x)

a) Đặt a + b = x ; a - b = y. Khi đó:
\(\left(a+b\right)^3-\left(a-b\right)^3\)
\(\Leftrightarrow x^3-y^3\)
\(\Leftrightarrow\left[x-y\right]\left[x^2+xy+y^2\right]\)
Thế lại vào ta có:
\(\Leftrightarrow\left[\left(a+b\right)-\left(a-b\right)\right]\left[\left(a+b\right)^2+\left(a+b\right)\left(a-b\right)+\left(a-b\right)^2\right]\)
\(\Leftrightarrow\left[\left(a-a\right)+\left(b+b\right)\right]\left[\left(a^2+b^2+2ab\right)+\left(a^2-b^2\right)+\left(a^2+b^2-2ab\right)\right]\)
\(\Leftrightarrow2b\left[\left(a^2+a^2+a^2\right)+\left(b^2-b^2+b^2\right)+\left(2ab-2ab\right)\right]\)
\(\Leftrightarrow2b\left[3a^2+b^2\right]\)

Mik làm tuỳ theo mình piết thôi nhé

a)   ( a + b )³- ( a - b )³= a³ + b³ - a³ - b³ = a³ - a³ + b³ - b³ = 0

b) tương tự như ở trên!!! Hơi khác một tí!!!

c)   ( 6x - 1 )² - ( 3x + 2 ) = ..........

gfvfvfvfvfvfvfv555

\(263^2+74.263+37^2\)

\(=69169+74.263+1369\)

\(=69169+19462+1369\)

\(=88631+1369\)

\(=90000\)

4^2.5=4^10

=1048576

3x^2-3x(-2+x)=36

3x^2 + 6x - 3x^2 = 36

6x = 36

x= 6