Math: multiplying radicals
Tutoring high school math, you realize that radicals are a problem for many. Today the math tutor gives brief coverage of multiplying radicals.
Consider the following example:
Simplify 3√(6)*4√(7)
Multiplying with radicals goes “number times number, radical times radical.” Like so:
Step 1: Number times number: In our case, 3 times 4, which gives 12.
Step 2: Radical times radical. In our case, √(6)√(7) gives √(42).
Putting it all together, we get
3√(6)*4√(7)=12√(42)
So far, so good. Beware, though: a simplification can creep in when the radicals are multiplied together:
Example 2: Simplify 3√(10)*7√(6)
Solution: Using number times number, radical times radical, we get
21√(60)
From my earlier post on simplifying radicals, we know we can’t just leave the answer 21√(60). After all, 60 contains the perfect square 4; we must simplify it as follows:
21√(60)=21√(4)√(15)=21*2√(15)=42√(15)
Note that if one of the factors is missing the number part, you just imagine it’s a 1 and proceed:
4√(7)*√(11)=4√(7)*1√(11)=4√(77)
On the other hand, one of the factors might be missing the radical part. Then, you just multiply the numbers together and tack the radical at the end:
6√(5)*(8)=48√(5)
Visit again for more tips on operations with radicals:)
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.
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