Question

How do you solve this question?

Answer 1

We can use the quadratic formula to solve this problem.

$\sf x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$

You've already listed the values for 'a', 'b', and 'c', so just plug them into the formula:

$\sf x=\dfrac{-(-12)\pm\sqrt{(-12)^2-4(4)(9)}}{2(4)}$

Simplify:

$\sf x=\dfrac{12\pm\sqrt{144-4(4)(9)}}{8}$

Multiply:

$\sf x=\dfrac{12\pm\sqrt{144-144}}{8}$

Subtract:

$\sf x=\dfrac{12\pm\sqrt{0}}{8}$

Take the square root:

$\sf x=\dfrac{12\pm 0}{8}$

It doesn't matter if you add or subtract something with 0, you'll end up with the same thing, so we have:

$\sf x=\dfrac{12}{8}\rightarrow\boxed{\sf 1\dfrac{1}{2}}$