Any non-zero number or expression divided by itself is equal to 1.1.1. 4545=12x+52x+5=1 \dfrac{45}{45}=1 \qquad \dfrac{2x+5}{2x+5}=1 4545ā=12x+52x+5ā=1 This is true for all values of the variables except the one(s) that makes the denominator 0.0.0.