Question

разложите на множители:
1)х^2+х-20=0
2)2х^2+7х-4=0
3)х^2-7x+10=0
4)3x^2-5x-2=0

Answer 1

1)xˇ2+x-20=(x+5)(x-4)=0, x1=-5, x2=4
2)2xˇ2+7x-4=0, D=49+32=81,VD=V(81)=9
   x1=1/4(-7+9)=1/4.2=2/4=1/2,x2=1/4(-7-9)=-4
   2(x-1/2)(x+4)=(2x-1)(x+4)
3)xˇ2-7x+10=(x-2)(x-5)=0, x1=2,x2=5
4)3xˇ3-5x-2=0, D=25+24=49, VD = V(49)=7
   x1=1/6(5+7)=1/6. 12=12/6=2
   x2=1/6(5-7)=1/6.(-2)=-2/6=-1/3
  3.(x-2)(x+1/3)=(x-2)(3x+1)