1000m³ - n³ = ( 10m )³ - n³ = ( 10m - n )( 100m² + 10mn + n² )
81a³ - ab² = a( 81a² - b² ) = a( 9a - b )( 9a + b )
- 8x - 16xy - 8y² = - 8( x + 2xy + y² )
5mn + 15m - 10n - 30 = 5m( n + 3 ) - 10( n + 3 ) = ( n + 3 )( 5m - 10 ) =
= 5( n + 3 )( m - 2 )
256 - b^4 = 4^4 - b^4 = ( 4^2 - b^2 )( 4^2 + b^2 ) = ( 4 - b )( 4 + b )( 16 + b^2 )
3)18а(2)-2b(2)=2(9a(2)-b(2)=2(3a-b)(3a+b)
(7a5 +2a3 +3a-12)-(4a5 -a3 +5a-7)-(3a5 -a3 -2a-5)=<u>7a5</u> +<em>2a3</em> +3a (-12) <u>-4a5</u> <em>+a3</em> -5a(+7)<u>-3a5</u> <em>+a3</em> +2a (+5)=0
3х^2+8х+2=0; делим на 3;
х^2+2*4/3х+16/9-16/9+2/3=0;
(х+4/3)^2=16/9-6/9=10/9;
х+4/3=+-(10^1/2)/3; х=-4/3+-(10^1/2)/3;
х1=(-4-10^1/2)/3; х2=(-4+10^1/2)/3.