Write a quadratic function with two real zeros.

The formula for quadratic equation is given by:

 x² - (sum)x + (product) = 0

so if we have real roots of 3 and 5 

 x² - (3 + 5)x + (3*5) = 0
 x² - 8x + 15 = 0

so if we have real roots of -3 and -6  

 x² - (-3 - 6)x + (-2*-6) = 0
 x² - (-9x) + 12 = 0
 x² + 9x + 12 = 0