Ben named his two dogs Changeup and Slider. If Changeup is 4 years older than Slider and the product of their ages is 21, how old is Slider?

Question

Please help me!!

Answer 1

If Slider is x years old

Changeup is x+4 years ld

 

x(x+4) = 21

I can see the answer is 3 and 7 years old

but let's finish the algebra:

 

x² + 4x = 21

x² + 4x - 21 = 0

(x+7)(x-3) = 0

x = -7 or x= 3

 

discarding the negative,

Slider is 3 years old.

Changeup is 3+4 = 7 years old