Question

ПОМОГИТЕ ПОЖАЛУЙСТА! ОЧЕНЬ СРОЧНО!!!!

Answer 1

$921 \ 1) (3m-a)(3m+a)-(2a+m)(3a-m)=9m ^{2} -a ^{2} -(6a ^{2} -2am+\+3am-m ^{2} )=9m ^{2} -a ^{2} -6a ^{2} +2am-3am+m ^{2} =10m ^{2} -7a ^{2} - \ -am \ \ 2) (x-4y)(x+3y)+(x-3y)(x+3y)= x^{2} +3xy-4xy-12y ^{2} + x^{2} - \ -9 y^{2} =2 x^{2} -21y ^{2} -xy$


$926 \ \ 1) x^{2} (x+2)-x(x+1) ^{2} =5x+9\ x^{3} +2 x^{2} -x( x^{2} +1+2x)-5x=9\ x^{3} +2 x^{2} - x^{3} -x-2 x^{2} -5x=9\-6x=9\x=9:(-6)\x=-1.5$

$2)(y-3) ^{2} +3(y+2)(y-2)=9+4y ^{2} \ y ^{2} +9-6y+3(y ^{2} -4)=9+4y ^{2} \ y ^{2} +9-y+ 3 y^{2} -12-9-4y ^{2} =0\-6y=-12\-6y=12\y=-2$

Answer 2

921
a)(3m-a)(a+3m)-(2a+m)(3a-m)=(3m-a)(3m+a)-(2a+m)(3a-m)=(9m²-a²)-(2a+m)(3a-m)=(9m²-a²)-(6a²-2am+3am-m²)=9m²-a²-6a²+2am-3am+m²=10m²-7a²-am
б)(x-4y)(x+3y)+(x-3y)(3y+x)=(x-4y)(x+3y)+(x-3y)(x+3y)=x²+3xy-4xy-12y²+x²-9y²=2x²-xy-21y²

926
х²(х+2)-х(х+1)²=5х-9
х³+2х²-х(х²+2х+1)=5х-9
х³+2х²-х³-2x²-x=5x-9
-x=5x-9
-6x=9
x=-1,5

(y-3)²+3(y+2)(y-2)=9+4y²
(y²-6y+9)+3(y²-4)=9+4y²
y²-6y+9+3y²-12=9+4y²
-6y=9+12-9
-6y=12
y=12:(-6)
у=-2