# Thread: Easy Multiple Choice

1. ## Easy Multiple Choice

A solution of x^3 - 9x^2 + 15x + 25 = 0 is x = 5. How many other (distinct) solutions are there?

A) 0 B)1 C)2 D)3 E)4

2. Originally Posted by Mr Rayon
A solution of x^3 - 9x^2 + 15x + 25 = 0 is x = 5. How many other (distinct) solutions are there?

A) 0 B)1 C)2 D)3 E)4
x = 5 is a zero means that (x - 5) is a factor. This helps you factorise the cubic:

$(x - 5)(x^2 - 4x - 5) = 0$.

So how many distinct real solutions does $x^2 - 4x - 5 = 0$ have?

3. Originally Posted by Mr Rayon
A solution of x^3 - 9x^2 + 15x + 25 = 0 is x = 5. How many other (distinct) solutions are there?

A) 0 B)1 C)2 D)3 E)4
What did you see when you plugged the graph into your calculator? What did you get when you divided out the given factor "x - 5" (or else plugged the given zero, x = 5, into the synthetic division) and then applied the Quadratic Formula to the remaining factor?