How can you evaluate (4a-2)/(3a+12) - (a-2)/(a+4) ?

1 Answer
Aug 3, 2015

(4a-2)/(3a+12)-(a-2)/(a+4)=1/3

Explanation:

In order to calculate the difference between the two terms, you need to write them with the same denominator. Notice that:

3a+12=3*(a+4)

Therefore:

(a-2)/(a+4)=1*(a-2)/(a+4)=3/3*(a-2)/(a+4)=(3(a-2))/(3(a+4))=(3a-6)/(3a+12)

Therefore:

(4a-2)/(3a+12)-(a-2)/(a+4)=(4a-2)/(3a+12)-(3a-6)/(3a+12)

=((4a-2)-(3a-6))/(3a+12)

=(4a-2-3a+6)/(3a+12)=(4a-3a+6-2)/(3a+12)=(a+4)/(3a+12)

=(a+4)/(3(a+4))=1/3