Isolate y on the left-hand side of the equation and substitute the values for x.
Equation: y=5-2x
x
y
- 1
7
0
5
3
- 1
Practice makes perfect
We want to solve the equation for y and then find the value of y for three values of x. We will do these things one at a time. Let's begin by solving the equation for y.
Now, we will use the rewritten equation to find the value of y for the given values of x. To do this, we substitute them into the equation and evaluate.
x
5-2x
y
- 1
5-2( - 1)
7
0
5-2( 0)
5
3
5-2( 3)
- 1
Extra
Real Life Example
We will focus on a real life example to better understand what we did. For an example, let's say we are going to a grocery shop with 5$ to buy some apples and oranges. Let's take a look at the prices.
Now, we will use the equation from the exercise, y+2x=5, where y is be the number of apples and x is the number of oranges. Notice that it models the problem we used as an example.
y+2 x=5
We would like to know how many apples we can buy if we buy 2 oranges. To find this, first we need to rewrite the equation to isolate y. Notice that we already did it in the solution above, let's take a look.
y+2x=5 ⇕ y=5-2x
Next, we need to substitute 2 for x and find the value of y. Let's do it!
