а) 16x^2 + 40xy+25y^2-8(2x^2+6xy-xy-3y^2) = 16x^2+40xy+25y^2-16x^2-48xy+8xy+24y^2=49y^2
б)4(x^2-3xy-6xy+18y^2)-(4x^2-2*18xy+81y^2)=4x^2-12xy-24xy+72y^2-4x^2+36xy-81y^2 = 9 y^2
(4х+5у)^2-8(2х-у)(х+3у)=4x+5y^2-8*2x+y*x+3y=4x+25y-16x+y*x=4x+25y-16x+x*y=4x+25y-17x*y=25y+4x-17x*y=25y+-13x*y=-13x+25y*y=-13x+25y
4(х-6у)(х-3у)-(2х-9у)^2=4*x+6y*x-3y-2x-9y=4x+6y*x-3y-2x-9y=6y+4x*x-3y-2x-9y=6y+4x-3y-2x-9y=4x+6y-3y-2x-9y
3=4x+3y-2x-9y=3y+4x-2x-9y=3y+2x-9y=2x+3y-9y=2x+-6y
Очень долго решала.
а) 16x^2 + 40xy+25y^2-8(2x^2+6xy-xy-3y^2) = 16x^2+40xy+25y^2-16x^2-48xy+8xy+24y^2=49y^2
б)4(x^2-3xy-6xy+18y^2)-(4x^2-2*18xy+81y^2)=4x^2-12xy-24xy+72y^2-4x^2+36xy-81y^2 = 9 y^2
(4х+5у)^2-8(2х-у)(х+3у)=4x+5y^2-8*2x+y*x+3y=4x+25y-16x+y*x=4x+25y-16x+x*y=4x+25y-17x*y=25y+4x-17x*y=25y+-13x*y=-13x+25y*y=-13x+25y
4(х-6у)(х-3у)-(2х-9у)^2=4*x+6y*x-3y-2x-9y=4x+6y*x-3y-2x-9y=6y+4x*x-3y-2x-9y=6y+4x-3y-2x-9y=4x+6y-3y-2x-9y
3=4x+3y-2x-9y=3y+4x-2x-9y=3y+2x-9y=2x+3y-9y=2x+-6y
Очень долго решала.