Question

What is the sum of the zeros of the function y = x² - 9x-10?

Answer 1

Answer: 9

Explanation:

Finding the zeros is the same as solving. Then, we will add the two solutions together.

Given:

y = x² - 9x - 10

Solving by Quadradic Formula:

`\displaystyle x=(-b\pm√(b^2-4ac) )/(2a)`

`\displaystyle x=(-(-9)\pm√((-9)^2-4(1)(-10)) )/(2(1))`

`\displaystyle x=(9\pm√(81+40) )/(2)`

`\displaystyle x=(9\pm√(121) )/(2)`

`\displaystyle x=(9+11)/(2),\;\;x=(9-11)/(2)`

x = 10, -1

Adding them together:

10 + -1 = 9