Find X in Rectangle: Area 40 cm² with Side Length 2x+4

Question

Rectangle ABCD has an area of

40 cm².

Side BC is equal to 5 cm.
Work out the value of x.

00:00 Determine the value of X

00:03 Apply the formula for calculating rectangle area

00:07 Side(AB) multiplied by side (BC)

00:11 Substitute the relevant values in the formula and solve for X

00:16 Open the parentheses correctly

00:22 Isolate X

00:26 This is the solution

Let's multiply side AB by side BC

We'll set up the data as follows:

$5(2x+4)=40$

Let's multiply 5 by each term in parentheses:

$10x+20=40$

We'll move 20 to the right side and change its sign accordingly:

$10x=40-20$

Now we get:

$10x=20$

Let's divide both sides by 10:

$x=2$