Solve x^2+8x+1>-2x^2+2x-2.
Antwoord 1 correct
Correct
Antwoord 2 optie
x=-1
Antwoord 2 correct
Fout
Antwoord 3 optie
x>-1
Antwoord 3 correct
Fout
Antwoord 4 optie
x<-1
Antwoord 4 correct
Fout
Antwoord 1 optie
All x except x=-1
Antwoord 1 feedback
Correct: x^2+8x+1>-2x^2+2x-2 \Leftrightarrow 3x^2+6x+3 > 0.
Define f(x)=3x^2+6x+3. We determine f(x)=0:
We use the quadratic equation. The discriminant is D=0, which implies that there is only one solution, x=-1.
Via the sign chart (for instance with f(-2)=3 and f(0)=3) we find that f(x) is strictly positive for all x expect for the zero x=-1.
Go on.
Define f(x)=3x^2+6x+3. We determine f(x)=0:
We use the quadratic equation. The discriminant is D=0, which implies that there is only one solution, x=-1.
Via the sign chart (for instance with f(-2)=3 and f(0)=3) we find that f(x) is strictly positive for all x expect for the zero x=-1.
Go on.
Antwoord 2 feedback
Wrong: (-1)^2+8(-1)+1=-6 \ngtr -6=-2(-1)^2+2(-1)-2.
Try again.
Try again.
Antwoord 3 feedback
Wrong: Pay attention to the sign chart.
Try again.
Try again.
Antwoord 4 feedback
Wrong: Pay attention to the sign chart.
Try again.
Try again.