(6а-в)²-(9а-в)(4а+2в)=36а²-12ав+в²-(36а²+18ав-4ав-2в²)=36а²-12ав+в²-36а²-18ав+4ав+2в²=-26ав+3в²=3в<span>²-26ав</span>
1) ( 1/b ) - ( 1/a ) = ( a - b ) / ab
2) ( a^2 - b^2 ) = ( a - b )( a + b )
3) [ ( a - b )( a + b ) / ab ] : [ ( a - b ) / ab ] = a + b
4) a = 1 3/7 ; b = 2 4/7
1 3/7 + 2 4/7 = 3 7/7 = 4
Ответ 4
Д=1-4*4*(-3)=1+48=49
√д=7
х1=1+7/8=1
х2=1-7/8=-3/4=-0.75
проверка
4-1-3=0
0=0
4*9/16 +0.75-3=2.25+0.75-3=0
0=0
ответ: 1;-0.75
в) а2 + ab-7a-7b = a*(a=b) - 7*(a+b)
в) 3x2 - 27 z2= 3*(x2-9z2)
№179
в) 2 c2+20cd+50 d2=2*( c2+10cd+25 d2)