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| Math Central | Quandaries & Queries |
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Question from Maria, a student: Add 3 radical 48 +11 radical 75. Write answer in simplest form. I tried to do the problem, but had a bit of a problem when I simplified each term in order to solve. Please help, giving step by step instructions to me. Thank you. |
Maria,
Let's try this
Write 7√45 - 8√20 in simplest form.
The key is to notice that 45 = 9 × 5 and 20 = 4 × 5, and that 9 and 4 are squares. Thus
√49 = √(9 × 5) = √9 × √5 = 3√5 and
√20 = √(4 × 5) = √4 × √5 = 2√5
Thus
7√45 - 8√20
= 7 × 3√5 - 8 × 2√5
= 21√5 - 16√5
= 5√5
Now try your problem,
Penny
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