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Solve A = (a + b)h/2 for h

Step by step, with the reason for every step · Literal equations · Algebra 1

Step by step

The question

Question: solve for h in A = (a + b)h/2.

We treat the other letters like numbers.

A = (a + b)h2

1 h on the left

h is on the right.

We swap the two sides, so h is on the left.

They are still equal.

(a + b)h2 = A

2 Remove the fraction

There is a fraction: over 2.

Times 2 removes it.

We do it on both sides.

2 × (a + b)h2 = 2 × A

2/2 is 1.

The fraction is gone.

Now we have (a + b)h = 2A.

(a + b)h = 2A

3 Remove the (a + b)

(a + b)h means (a + b) times h.

We want just h.

To remove times (a + b), we divide by (a + b).

We do it on both sides.

(a + b)h(a + b) = 2A(a + b)

(a + b) divided by (a + b) is 1.

So just h is left.

So h = 2A/(a + b).

h = 2A(a + b)

4 Check

Let's check with numbers.

We pick A = 3, a = 2, b = 4.

Our answer gives h = 1.

h = 2(3)2 + 4 = 66 = 1

Now we put all the numbers into the start.

First the left side.

Left: 3

Now the right side.

Right: (2 + 4)(1)2 = 6 × 12 = 3

Both sides are 3.

So our answer is right!

Both sides equal 3

Let's look back.

First: h on the left.

Then: remove the fraction.

Then: remove the (a + b).

Last: check.

Answer
h = 2A(a + b)

Your turn

Try this one yourself, then check:

S = (a + l)n2
Show the answer
n = 2S(a + l)

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