Question

Answer 1

7:

a: \(\left(x^2+4y^2\right)\left(x+2y\right)\left(x-2y\right)\)

\(=\left(x^2+4y^2\right)\left(x^2-4y^2\right)\)

\(=x^4-16y^4\)

b: \(\left(x-1\right)\left(x+1\right)\left(x^2+1\right)\left(x^4+1\right)\)

\(=\left(x^2-1\right)\left(x^2+1\right)\left(x^4+1\right)\)

\(=\left(x^4-1\right)\left(x^4+1\right)\)

\(=x^8-1\)

6:

a: \(\left(a+2b\right)^2=a^2+4ab+4b^2\)

=>*=2b

b: \(\left(x-4a\right)^2=x^2-8ax+16a^2\)

=>*=4a

c: \(\left(0.4x-5y\right)^2=0.16x^2-2\cdot0.4x\cdot5y+25y^2\)

=>*=0,4x

d: \(\left(3x-0.5y\right)^2=9x^2+0.25y^2+2\cdot3x\cdot\left(-1\right)\cdot0.5y\)

\(=9x^2+0.25y^2-1.5xy\)

=>*=-1,5xy