Question
Solve the following equation by using formula :
$25x^2 + 30x + 7 = 0$
$25x^2 + 30x + 7 = 0$
✓
Answer
$\begin{aligned} & 25 x^2+30 x+7=0 \\ & \text { Here } a=25, b=30, c=7 \\ & D=b^2-4 a c \\ & =(30)^2-4 \times 25 \times 7 \\ & =900-700 \\ & =200 \\ & \because x=\frac{-b \pm \sqrt{D}}{2 a} \\ & =\frac{-30 \pm \sqrt{200}}{2 \times 25} \\ & =\frac{-30 \pm \sqrt{100 \times 2}}{50} \\ & =\frac{-30 \pm 10 \sqrt{2}}{50} \\ & =\frac{-3 \pm \sqrt{2}}{5} \\ & \therefore x_1=\frac{-3+\sqrt{2}}{5} \text { and } x_2=\frac{-3-\sqrt{2}}{5}\end{aligned}$
Hence $x=\frac{-3+\sqrt{2}}{5}, \frac{-3-\sqrt{2}}{5}$.
Hence $x=\frac{-3+\sqrt{2}}{5}, \frac{-3-\sqrt{2}}{5}$.
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