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Solve 5/(2x) + 1/x = 7/4

Step by step, with the reason for every step · Rational equations · Algebra 2

Step by step

The question

Question: solve 5/2x + 1/x = 7/4.

52x + 1x = 74

First: a bottom can never be 0.

x at the bottom can't be 0.

So x ≠ 0.

x ≠ 0

1 Remove the fractions

The bottoms are 2x, x and 4.

4x can be divided by all of them.

We multiply every part by 4x.

We do it on both sides, so they stay equal.

4x × 52x + 4x × 1x = 4x × 74

4x divided by 2x is 2.

4x divided by x is 4.

4x divided by 4 is x.

Write what is left.

No more fractions!

10 + 4 = 7x

2 Group like terms

Terms are the parts between the + and − signs.

Like terms are the same kind: same letters, same powers.

Plain numbers go together.

10 + 4 = 14.

10 + 4 = 14

Now we have 14 = 7x.

14 = 7x

Let's swap the two sides, so x is on the left.

7x = 14

3 Remove the 7

7x means 7 times x.

We want just x.

To remove times 7, we divide by 7.

We do it on both sides, so they stay equal.

7x7 = 147

7 divided by 7 is 1.

So just x is left.

14 divided by 7 is 2.

147 = 2

So x = 2!

x = 2

4 Check

Let's check: put 2 in place of x.

First the left side.

Left: 52(2) + 12 = 54 + 12 = 54 + 24 = 74

Now the right side.

Right: 74

Both sides are 7/4.

So x = 2 is right!

Both sides equal 74

Let's look back.

First: remove the fractions.

Then: group like terms.

Then: remove the 7.

Last: check.

Answer
x = 2

Your turn

Try this one yourself, then check:

72x + 4x = 154
Show the answer
x = 2

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