Each side of a square plot is x metres. When each side is made 3 m longer, the area becomes 81 m².
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Each side of a square plot is metres. When each side is made longer, the area becomes . Write a quadratic equation in standard form for , and check that is a root.
Need a reminder? The key ideaShow
A quadratic equation can be written as with . Expand brackets and collect the terms on one side before you decide. A number is a root when putting it in makes the left side .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The equation. .
Step 2. Standard form. , that is .
Step 3. Check . .
Answer: ; the left side is at , so is a root and the side was .
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