Question

question 3 of 8
$y = \frac{-b\pm\sqrt{b^{2}-4ac}}{2a}$
$y = \frac{-(-3)\pm\sqrt{(-3)^{2}-4(1)(-9)}}{2(1)}$
part: 2 / 4
part 3 of 4
simplify.
$y = \frac{\square\pm\sqrt{\square}}{\square}$

Explanation:

Step1: Simplify the numerator -(-3)

The double - negative makes it positive. So -(-3)=3.
$y=\frac{3\pm\sqrt{(- 3)^{2}-4(1)(-9)}}{2(1)}$

Step2: Calculate $(-3)^2$

$(-3)^2 = (-3)\times(-3)=9$.
$y=\frac{3\pm\sqrt{9 - 4(1)(-9)}}{2(1)}$

Step3: Calculate $4(1)(-9)$

$4\times1\times(-9)=-36$.
$y=\frac{3\pm\sqrt{9-(-36)}}{2(1)}$

Step4: Simplify the expression inside the square - root

$9-(-36)=9 + 36=45$. And $2(1)=2$.
$y=\frac{3\pm\sqrt{45}}{2}$

Answer:

$y=\frac{3\pm\sqrt{45}}{2}$