Площадь равна произведению сторон(А*В=480)
В)-x^2-4x=0
-x(x+4)=0
x=0 или x=-4
<span>г)x^3-x^2=0
x^2(x-1)=0
x=0 или x=1</span>
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
3^(x+y)=1/9
lg (x-2y) = lg ( 2x+5)
Одз x>2y 2x+5>0 x>-2.5
3^(x+y)=3^-2
x-2y=2x+5
x+y=-2
x+2y=-5 вычитаем первое из второй
x+2y-x-y=-5+2
y=-3
x=1
(1 -3) по одз проходит