3x² - 4x + a = 0
x₁ = - 2
3 * (- 2)² - 4 * (- 2) + a = 0
3 * 4 + 8 + a = 0
20 + a = 0
a = - 20
3x² - 4x - 20 = 0
D = (- 4)² - 4 * 3 * (- 20) = 16 + 240 = 256 = 16²
16x²-24xy+9y²-6x²+10xy-3xy+5y²=10x²-14xy+14y²
<span>А) 2а(а-3)-2а(4+а) =2a (a-3 -4-a)=2a (-7)=-14a</span>
<span>Б) (1-х)(х+1)+(х-1) = (1-х)(1+х)-(1-х)=(1-x) (1+x-1)=x(1-x) = x-x^2</span>