Gabby solved x2 - 3x = 4 as shown below:

x2 - 3x - 4 = 0

(x - 4) (x + 1) = 0

x = - 4 and x = 1

Caitlyn says Gabby is wrong and believes this is the solution:

x2 - 3x - 4 = 0

(x - 4) (x + 1) = 0

x = 4 and x = - 1

Is Gabby or Caitlyn correct? What mistake was made by the incorrect girl? Type your response in the box provided.

Question

Rocha

Mathematics

18 October, 04:54

Gabby solved x2 - 3x = 4 as shown below:

x2 - 3x - 4 = 0

(x - 4) (x + 1) = 0

x = - 4 and x = 1

Caitlyn says Gabby is wrong and believes this is the solution:

x2 - 3x - 4 = 0

(x - 4) (x + 1) = 0

x = 4 and x = - 1

Is Gabby or Caitlyn correct? What mistake was made by the incorrect girl? Type your response in the box provided.

+1

Answers (1)

Know the Answer?

Maritza · Answer 1

Caitlyn is correct.

Both factored correctly but the reason Gabby is wrong is because of the Zero Product Property, which says if (x-4) (x+1) = 0, then (x-4) = 0 or (x+1) = 0.

If (x-4) = 0, then the value of x must be 4.

If (x+1) = 0, then the value of x must be - 1.