What is the domain of (4/(a+1))-(5/a) = (20/(a^2+a))?

1 Answer
Oct 26, 2015

a={-25}

Explanation:

[1]" "4/(a+1)-5/a=20/(a^2+a)

Combine 4/(a+1) and -5/a by making them have the same denominator.

[2]" "(4(a))/(a(a+1))-(5(a+1))/(a(a+1))=20/(a^2+a)

[3]" "(4(a)-5(a+1))/(a(a+1))=20/(a^2+a)

[4]" "(4a-5a-5)/(a^2+a)=20/(a^2+a)

[5]" "(-a-5)/(a^2+a)=20/(a^2+a)

Multiply both sides by (a^2+a) to remove the denominator.

[6]" "cancel(a^2+a)((-a-5)/cancel(a^2+a))=cancel(a^2+a)(20/cancel(a^2+a))

[7]" "-a-5=20

[8]" "-a=25

[9]" "color(blue)(a=-25)