Question

Решите неравенство 4x^2+10х-20<=(x+2)^2

Answer 1

4х^2+10х-20<=(X+2)^2

4X^2+10x-20<=x^2+4x+4

4x^2-x^2+10x-4x-20-4<=0

3x^2+6x-24<=0

D=b^2-4ac

D=36-4*3*(-24)=324

x1,2=(-b^2+-корень изD)/2a

x1=(-6+18)/(2*3)=2

x2=(-6-18)/(2*3)=-4

 

Answer 2

 4x^2+10х-20<=(x+2)^2

 4x^2+10х-20<=x^2+4x+4

3x^2+6x-24<=0

x^2+2x-8<=0

x1=-4   x2=2

xe[-4,2]