Solve $7x^2-4x+2 > -3x^2+5x$.
Antwoord 1 correct
Correct
Antwoord 2 optie
$\frac{2}{5}$
Antwoord 2 correct
Fout
Antwoord 3 optie
$\frac{4}{5}$
Antwoord 3 correct
Fout
Antwoord 4 optie
$x< \frac{4}{5}$ or $x>1$
Antwoord 4 correct
Fout
Antwoord 1 optie
$x< \frac{2}{5}$ or $x>\frac{1}{2}$
Antwoord 1 feedback
Correct: $7x^2-4x+2 > -3x^2+5x \Leftrightarrow 10x^2-9x+2 > 0$.
Define $f(x)=10x^2-9x+2$. We determine the zeros of $f(x)$, hence we solve $f(x)=0$:
$D=9^2 - 4\cdot 10 \cdot 2 = 1$.
Hence, $x=\frac{2}{5}$ or $x=\frac{1}{2}$.
Via the sign chart (with for instance $f(0)=2$, $f(\frac{9}{20})=-0.025$ and $f(1)=3)$ we find $x< \frac{2}{5}$ or $x>\frac{1}{2}$.
Go on.
Define $f(x)=10x^2-9x+2$. We determine the zeros of $f(x)$, hence we solve $f(x)=0$:
$D=9^2 - 4\cdot 10 \cdot 2 = 1$.
Hence, $x=\frac{2}{5}$ or $x=\frac{1}{2}$.
Via the sign chart (with for instance $f(0)=2$, $f(\frac{9}{20})=-0.025$ and $f(1)=3)$ we find $x< \frac{2}{5}$ or $x>\frac{1}{2}$.
Go on.
Antwoord 2 feedback
Antwoord 3 feedback
Antwoord 4 feedback