Quadratic Word Problems

Question

The difference of the square of a number and 18 is equal to seven times the number find the negative solution

Answer 1

x^2 - 18 = 7x

x^2 -7x -18 = 0

(x-9)(x+2) = 0

x+2 =0

x =-2 = the only negative solution

(-2)^2 -18

= 4-18

=-14

= 7(-2)