Exercise 1 Page 44

To solve for z we need to isolate it by subtracting 3 from both sides of the equation. We want to subtract because addition and subtraction are inverse operations - they cancel each other out. This is allowed by the Subtraction Property of Equality.

z+3=-6

SubEqn

LHS-3=RHS-3

z+3-3=-6-3

SubTerms

Subtract terms

z=-9

We will check our solution by substituting this result back into the original equation and simplifying. If doing so results in an identity, our solution is correct.

z+3=-6

Substitute

z= -9

-9+3? =-6

AddTerms

Add terms

-6=-6 ✓

An identity occurs when the left-hand side and the right-hand side of an equation are equal to one another. Since substituting z=-9 resulted in an identity, our solution is correct.