Question

Harry is trying to solve the equation y = 2x^2 − x − 6 using the quadratic formula. He has made an error in one of the steps below. Find the step where Harry went wrong.

Answer 1

He made a mistake in step #2. It seemed to be a trivial mistake because it involved signs, but it still had a great impact. Since step#2, his solution was already wrong.

Instead of
(-1)²-4(2)(-6) = 1 + 48 = 49

What he did is
(-1)²-4(2)(-6) = -1 + 48 = 47