5a^4-20a²b+20b²=5*(a²-4a²b+4b²)=5*(a²-2b)²
(x+y)+(x-y)=x+y+x-y=2x
(x+y)-(x-y)=x+y-x+y=2y
X+y=3<span>X^2-xy-y^2=1
х=3-у
(3-у)</span>²-у(3-у)-у²=1
9-6у+у²-3у+у²-у²=1
у²-9у+8=0
у1=1
у2=8
х1=3-1=2
х2=3-8=-5
А) 3x²-4x-(3x²-5x-(7x²-3))=
=3x²-4x-(3x²-5x-7x²+3)=
=<u>3x²</u>-<em>4x</em>-<u>3x²</u>+<em>5x</em>+<u>7x²</u>-3 =
=7x²+x-3
б) (x³+2x²-(x+1)) -(x²-(7x³+2))=
=(x³+2x²-x-1) - (x²-7x³-2) =
= <u>x³</u>+2x²-<em>x</em>-1 - x²+<u>7x³</u>+2 =
=8x³ +x² -x+1
в) -(12p⁴-(10p⁴-3p³-(7p²-4p³-(8p²-4p))))=
= -(12p⁴-(10p⁴-3p³-(7p²-4p³-8p²+4p)))=
= -(12p⁴-(10p⁴-3p³-7p²+4p³+8p²-4p))=
= -(<u>12p⁴</u>-<u>10p⁴</u>+3p³+<em>7p²</em>-4p³-<em>8p²</em>+4p)=
= -(2p⁴-p³-p²+4p)=
=-2p⁴+p³+p²-4p
г) 3.5n²-((11.4n⁴+1.3n⁵)-(7n⁴+2.5n³)+(3n⁴+(2n²-2n⁴)))=
=3.5n²-(11.4n⁴+1.3n⁵-7n⁴-2.5n³+3n⁴+2n²-2n⁴)=
=3.5n²-11.4n⁴<u>-1.3n⁵</u>+7n⁴+<em>2.5n³</em>-3n⁴-2n²+2n⁴=
=-1.3n⁵-5.4n⁴+2.5n³+1.5n²
д) 4x+(3x-(5x-(7x+5x²)+9x³)-3x³)=
=4x+(3x-(5x-7x-5x²+9x³)-3x³)=
=4x+(3x-5x+7x+5x²-9x³-3x³)=
=<em>4x+3x-5x+7x</em>+5x²<u>-9x³-3x³</u>=
=-12x³+5x²+9x