Rectangle ABCD has an area of
40 cm².
Side BC is equal to 5 cm.
Work out the value of x.
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Rectangle ABCD has an area of
40 cm².
Side BC is equal to 5 cm.
Work out the value of x.
Let's multiply side AB by side BC
We'll set up the data as follows:
Let's multiply 5 by each term in parentheses:
We'll move 20 to the right side and change its sign accordingly:
Now we get:
Let's divide both sides by 10:
2
Look at the rectangle ABCD below.
Side AB is 6 cm long and side BC is 4 cm long.
What is the area of the rectangle?
It doesn't matter! For rectangles, area = length × width works the same regardless of which side you call length or width. Just multiply the two given measurements.
When you have , the 5 must multiply everything inside the parentheses. This gives you .
Check your work! In this problem, x represents part of a length measurement, so it should be positive. A negative x would mean a negative length, which doesn't make sense.
Yes! You could divide both sides by 5 first: , then solve. Both methods work, so use whichever feels easier to you.
Substitute x = 2 back into the original measurements: Side AB = cm, Side BC = 5 cm. Check: cm² ✓
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