Ms. Pacheco = P
Mr. Richards = R
Mr. Edwards = E
P = R + 3
E = 2R
R + E = 81
81 = R + 2R
81 = 3R
81 ÷ 3 = R
R = 27
P = R + 3
P = 27 + 3
P = 30
E = 2R
E = 2×27
E = 54
First, we should add 1 to both sides to isolate the variable:
3x = 12
Now that x is isolated, we divide by 3:
x = 4
( - ∞, 3) ∪ (3, ∞ )
The domain is the set of values of x which make f(x) defined
The denominator of f(x) cannot be zero as this would make f(x) undefined. Equating the denominator to zero and solving gives the value that x cannot be.
solve x - 3 = 0 ⇒ x = 3
domain : (- ∞, 3) ∪ (3, ∞ )