Question

Solve the equation by factoring. Check your answer by graphing.

x² - 4x = 5
Step 1 - Write the equation in the form x² + bx + c = 0.
4.
Step 2 Factor and solve the equation using the Zero Product Property.
Step 3 Graph the related function (x) = x² + bx + c.
The related function is f(x) =
x
f(x)
1
The solutions of the equation are x =
and x =
-7 -6
Y
Pairs of
Factors for
C =
6
5
4
3
2
1
--3-2-10 1
-2
-3
4
-5
2
Sum of
Factors
b
3
4
5
?
6

Answer 1

We have the equation
x^2-4x=5

But if we replace and pass the +5 with the opposite sign -5 we have a square trinomial of the form ax^2+-mx+-c=0 where the two values that multiplied are c and a respectively the sum of their products is mx.
So x^2-4x-5=0

Then x^2=x x ; -5= -5 x 1 and -5x + x = -4
And we finally have x= -1 or x= 5
because x+1=0; x=-1 and x-5=0; x=5