bài 1: rút gọn biểu thức
1. x(x-1)(x+1) - (x+1)(x2-x+1)
2. (2a2+2a+1) ( 2a2-2a+1) - (2a2+1)2
3. (a2+b2+c2)2 - (a2-b2-c2)2
4. (a+b+c+d) (a+b+c+d)
5. (a-5)2 (a2+10a+25)
6. (3x\(^3\)+3x+1) (3x\(^3\)-3x+1) - (3x\(^3\)+1)2
( MONG CÁC BẠN GIÚP MÌNH NHA. CẢM ƠN>>>>>>>))))))
\(\left(x+1\right)\left(x^2-x-x^2+x-1\right)=-\left(x+1\right)\)
\(\left(2a^2+1\right)^2-4a^2-\left(2a^2+1\right)^2=-4a^2\)
\(\left(a^2+b^2+c^2+a^2-b^2-c^2\right)\left(a^2+b^2+c^2-a^2+b^2+c^2\right)=2a^2\left(2b^2+2c^2\right)=4a^2b^2+4a^2c^2\)
\(\left(a-5\right)^2\left(a+5\right)^2=\left(a^2-25\right)^2\)
\(\left(3a^3+1\right)^2-9a^2-\left(3a^3+1\right)^2=-9a^2\)