This lesson is an introduction to algebra
How to solve a simple algebra equation
Solving an equation is finding a missing value in the equation. For example you could be asked: solve 2 + x = 4 or Find the value of X in the equation.
What does x mean? X simply means an unknown value, we can use any alphabetical letter we want to represent this missing value, it’s also called (variable).
In the above equation (2 + x = 4) we have to find the value of X. In other words, find a number that we add to 2 and get 4. You probably guessed the answer which is 2 (2 + 2 = 4). When we replaced the X by 2 we checked whether the equation makes sense or not (is 2 + 2 equals 4) and the answer is yes.
So far, we solved equations by guessing, that works for simple equations. However, for more complex equations we need to use Solving by inverse operation.
Take a look at the following equation: 2x + 4 = 20
(!) 2x simply means (2 times x) however, we don’t write the times sign in algebra equation so when you see a number with a letter besides each other, they are by default times each other.
How would you solve an equation like this? Let’s break that down.
(2x + 4 = 20) Wouldn’t it be easier if we get rid of the 4? we can easily do that by subtracting 4 from both sides as if we subtract 4 from 4 we have 0.
So 2x + 4 – 4 = 20 – 4
After subtracting: 2x = 16
Now we need to get rid of the 2 and have the x alone on its side. So we can divide both sides by 2 (opposite of multiplication is division)
So 2x ÷ 2 = 16 ÷ 2
After dividing x = 8
And we have the result x is equal to 8.
Let’s sum that up
2x + 4 = 20
2x + 4 – 4 = 20 – 4
2x = 16
2x ÷ 2 = 16 ÷ 2
x = 8