Question
Solve the following quadratic equation.
(2x + 3)2 = 25
(2x + 3)2 = 25
✓
Answer
$\begin{array}{l}4 x^2+12 x+9-25=0 \Rightarrow 4 x^2+12 x-16=0 \\ \Rightarrow x^2+3 x-4=0 \text { compare with } a x^2+b x+c=0 \\ \Rightarrow a=1, b=3 \text { and } c=-4 \\ \therefore b^2-4 a c=3^2-4(1)(-4) \\ =9+16 \\ =25 \\ x=\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\end{array}$
$\begin{array}{l}\Rightarrow x=\frac{-3 \pm \sqrt{25}}{2 \times 1} \\ \Rightarrow x=\frac{-3 \pm 5}{2} \\ \Rightarrow x=\frac{-3+5}{2} \text { or } x=\frac{-3-5}{2} \\ \Rightarrow x=\frac{2}{2} \text { or } x=\frac{-8}{2} \\ \Rightarrow x=1 \text { or } x=-4\end{array}$
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