Помогите. 1. Преобразуйте выражение в многочлен а) (2h-3)^2 б) (x+5y)^2 в) (2/3a-b)...

1.
а) $(2h-3)^2$ = $4h^2-12h+9;$
б) $(x+5y)^2$ = $x^2+10xy+25y^2;$
в) $(\frac{2}{3}a-b)(\frac{2}{3}a+b)$ = $(\frac{2}{3}a)^2-b^2$ = $\frac{4}{9}a^2-b^2.$
2.
а) $(r+2)(r-5)(r+4)^2$ = $(r^2-3r-10)(r+4)^2$ = $(r^2-3r-10)(r^2+8r+16)$ = $r^4+8r^3+16r^2-3r^3-24r^2-48r-10r^2-80r-160$ = $r^4+5r^3+16r^2-24r^2-48r-10r^2-80r-160$ = $r^4+5r^3-8r^2-48r-10r^2-80r-160$ = $r^4+5r^3-18r^2-48r-80r-160$ = $r^4+5r^3-18r^2-128r-160;$
б) $3(a+2b)^2-12ab$ = $3(a^2+4ab+4b^2)-12ab$ = $3a^2+12ab+12b^2-12ab$ = $3a^2+12b^2$ = $3(a^2+4b^2);$
в) $(m-1)(m^2+m+1)-m^3$ = $m^3-1^3-m^3$ = $-1^3$ = $-1.$