Упростите 1) 3x(x-6)-(2x-5)(2x+5) 2) (c+7)^2-2c(3c-2) 3)12ab+(2a-3b)^2

Question

Упростите
1) 3x(x-6)-(2x-5)(2x+5)
2) (c+7)^2-2c(3c-2)
3)12ab+(2a-3b)^2

Answer 1

1) =3х^2-18x-4x^2+25=-x^2-18x+25
2) =c^2+14c+49-6c^2+4c=-4c^2+18c+49
3) =12ab+4a^2-12ab+9b^2=4a^2+9b^2