Question
Solve the following equation by using quadratic formula and give your answer correct to 2 decimal places : $4x^2 – 5x – 3 = 0$
✓
Answer
Given equation $4 x^2-5 x-3=0$
Comparing with $a x^2+b x+c=0$, we have $a = 4, b = -5, c = -3$
$\because x =\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}$
$=\frac{-(-5) \pm \sqrt{(-5)^2-4 \times 4 \times(-3)}}{2 \times 4}$
$=\frac{5 \pm \sqrt{25+48}}{8}$
$=\frac{5 \pm \sqrt{73}}{8}$
$=\frac{5 \pm 8.544}{8}$
$=\frac{5+8.544}{8}$ or $\frac{5-8.544}{8}$
$=\frac{13.544}{8}$ or $\frac{-3.544}{8}$
$= 1.693$ or $-0.443$
$= 1.69$ or $-0.44. ...($correct to $2$ demical places$)$
Comparing with $a x^2+b x+c=0$, we have $a = 4, b = -5, c = -3$
$\because x =\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}$
$=\frac{-(-5) \pm \sqrt{(-5)^2-4 \times 4 \times(-3)}}{2 \times 4}$
$=\frac{5 \pm \sqrt{25+48}}{8}$
$=\frac{5 \pm \sqrt{73}}{8}$
$=\frac{5 \pm 8.544}{8}$
$=\frac{5+8.544}{8}$ or $\frac{5-8.544}{8}$
$=\frac{13.544}{8}$ or $\frac{-3.544}{8}$
$= 1.693$ or $-0.443$
$= 1.69$ or $-0.44. ...($correct to $2$ demical places$)$
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