Question

One of the solutions to x2 − 2x − 15 = 0 is x = −3. What is the other solution?

Answer 1

If you factor the equation you can see what the solutions are.  Two factor a quadratic of the form ax^2+bx+c, find two values which satisfy two conditions...

jk=ac=-15 and j+k=b=-2 so j and k must be -5 and 3 so the factors are:

(x-5)(x+3)

So the other solution is x=5

Answer 2

The answer is D) X=5 on E2020 (: