a Start by undoing the subtraction using its inverse operation and continue isolating x following the Properties of Equality.
B
b This time use the inverse operation to multiplication and continue isolating x following the Properties of Equality.
C
c Which way of solving the equation was easier for you?
A
a x=4.
B
b Same result.
C
c See solution.
Practice makes perfect
a We are given the equation
2x-1 = 7,
and asked to solve it by undoing the subtraction first. To do this, we need to use its inverse operation. Namely, we need to add 1 to both sides. We can then continue to isolate x using inverse operations and the Properties of Equality.
b We will solve the equation shown above again, but this time we will undo the multiplication first. For this, we will start by dividing by 2. Then we can continue to isolate x using inverse operations and the Properties of Equality.
Notice that we arrived to the same solution as before, x=4.
c Although both methods arrived to the same result, starting by undoing the subtraction produced fewer steps. However, this is only our opinion. As long as you are using the Properties of Equality and the order of operations correctly, either method is equally valid.
