Упр.15.2 ГДЗ Мерзляк Поляков 7 класс (Алгебра)

1) (m-n)(m+n); 2) (x-1)(x+1);
3) (9-y)(9+y); 4) (3b-1)(3b+1);
5) (10m-7)(10m+7); 6) (4a-b)(b+4a);
7) (5b+1)(1-5b); 8) (3x-5y)(3x+5y);
9) (13c-10d)(13c+10d); 10) (8m+11n)(11n-8m).

1. $$ (m-n)(m+n)=m^2-n^2 $$
2. $$ (x-1)(x+1)=x^2-1 $$
3. $$ (9-y)(9+y)=9^2-y^2=81-y^2 $$
4. $$ (3b-1)(3b+1)=(3b)^2-1^2=9b^2-1 $$
5. $$ (10m-7)(10m+7)=(10m)^2-7^2=100m^2-49 $$
6. $$ (4a-b)(b+4a)=(4a-b)(4a+b)=(4a)^2-b^2=16a^2-b^2 $$
7. $$ (5b+1)(1-5b)=1^2-(5b)^2=1-25b^2 $$
8. $$ (3x-5y)(3x+5y)=(3x)^2-(5y)^2=9x^2-25y^2 $$
9. $$ (13c-10d)(13c+10d)=(13c)^2-(10d)^2=169c^2-100d^2 $$
10. $$ (8m+11n)(11n-8m)=(11n+8m)(11n-8m)=(11n)^2-(8m)^2=121n^2-64m^2 $$

Ответ

1) $$m^2-n^2$$; 2) $$x^2-1$$; 3) $$81-y^2$$; 4) $$9b^2-1$$; 5) $$100m^2-49$$; 6) $$16a^2-b^2$$; 7) $$1-25b^2$$; 8) $$9x^2-25y^2$$; 9) $$169c^2-100d^2$$; 10) $$121n^2-64m^2$$.