Rationalise the denominator of 1/(√7 - √5).
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Rationalise the denominator of . Check your answer with its value to three decimal places.
Need a reminder? The key ideaShow
To clear a root from the bottom, multiply the top and the bottom by the same number: by for , and by the conjugate for . The value does not change.
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 conjugate. .
Step 2. Check. and . The sum is , and half of it is .
Answer: .
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