Упр.6.113 ГДЗ Дорофеев Суворова 7 класс (Алгебра)

б) (а + b)(2а + 3b);
в) (3с + а)(2с — а);
г) (6z — у)(2z — у);
д) (5x — с)(х — 5с);
е) (4m + 3n)(4m + 3n);
ж) (3у — 2v)(3у + 2v);
з) (10x + 3z)(10х — 5z).

1. $$ (2x-y)(x+y)=2x^2+2xy-xy-y^2=2x^2+xy-y^2 $$
2. $$ (a+b)(2a+3b)=2a^2+3ab+2ab+3b^2=2a^2+5ab+3b^2 $$
3. $$ (3c+a)(2c-a)=6c^2-3ac+2ac-a^2=6c^2-ac-a^2 $$
4. $$ (6z-y)(2z-y)=12z^2-6yz-2yz+y^2=12z^2-8yz+y^2 $$
5. $$ (5x-c)(x-5c)=5x^2-25cx-cx+5c^2=5x^2-26cx+5c^2 $$
6. $$ (4m+3n)(4m+3n)=16m^2+12mn+12mn+9n^2=16m^2+24mn+9n^2 $$
7. $$ (3y-2v)(3y+2v)=9y^2+6yv-6yv-4v^2=9y^2-4v^2 $$
8. $$ (10x+3z)(10x-5z)=100x^2-50xz+30xz-15z^2=100x^2-20xz-15z^2 $$

Ответ

а) $$2x^2+xy-y^2$$; б) $$2a^2+5ab+3b^2$$; в) $$6c^2-ac-a^2$$; г) $$12z^2-8yz+y^2$$; д) $$5x^2-26cx+5c^2$$; е) $$16m^2+24mn+9n^2$$; ж) $$9y^2-4v^2$$; з) $$100x^2-20xz-15z^2$$.