Question

why can't we take the numbers as -10 and 3

Answer 1

because product of -10 and 3 is not equal to 330 we have to take those numbers whose product will be 330 or when we add or subtract then middle term number will come which is 7x

Answer 2

Given Equation is x^2 + 7x - 330 = 0

= > x^2 - 15x + 22x - 330 = 0

= > x(x - 15) + 22(x - 15) = 0

= > (x + 22)(x - 15) = 0.

= > x = 15,-22

Hope this helps!