Question
Solve the following quadratic equation by formula method
$3 y^2-20 y-23=0$
$3 y^2-20 y-23=0$
✓
Answer
$\begin{aligned} & a=3, b=-20, c=-23 \\ & x=\frac{-b \pm \sqrt{b^2-4 a c}}{2 a} \\ & =\frac{20 \pm \sqrt{400-4(3)(-23)}}{6} \\ & =\frac{20 \pm \sqrt{400+276}}{6} \\ & =\frac{20 \pm \sqrt{676}}{6} \\ & =\frac{20 \pm 26}{6} \\ & =\frac{2(10 \pm 13)}{6} \\ & =\frac{(10 \pm 13)}{3} \\ & =\frac{10+13}{3} \text { or } \frac{10-13}{3}\end{aligned}$
$
=\frac{23}{3} \text { or } \frac{-3}{3}=\frac{23}{3} \text { or }-1
$
The solution set is -1 and $\frac{23}{5}$
$
=\frac{23}{3} \text { or } \frac{-3}{3}=\frac{23}{3} \text { or }-1
$
The solution set is -1 and $\frac{23}{5}$
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