Question

Прошу, помогите!!! 20 БАЛЛОВ

Answer 1

1. 4x^2+6xy-(x^2+2xy+y^2)
4x^2+6xy-x^2-2xy-y^2
3x^2+4xy-y^2
2. y=4x-9
3x+7*(4x-9)=-1; 3x+28x-63=-1;31x=62;x=2
y=4*2-9=-1
4.a)3a*(a-3b)
b)x*(x-25)
5.a)5^18*5^3/5^21=5^18+3/5^21=5^21/5^21=5^21-21=5^0=1
b)(65-52)*(65+52)+(39-26)*(39+26)/2401-3528+1296=13*117+13*65/169=1521+845/169=2366/169=14