asked 127k views
4 votes
How too do tjis sum pls sum body​

How too do tjis sum pls sum body​-example-1
asked
User Damodar
by
7.5k points

1 Answer

5 votes

I assume you're referring to 25.

Find the prime factorizations of the numbers under the cube root:


40=2^3\cdot5


625=5^4


320=2^6\cdot5

The cube roots share a common factor of
\sqrt[3]5, so that


2\sqrt[3]{40}+3\sqrt[3]{625}+4\sqrt[3]{320}=2\sqrt[3]{2^3\cdot5}+3\sqrt[3]{5^4}+4\sqrt[3]{2^6\cdot5}


=\sqrt[3]5\left(2\sqrt[3]{2^3}+3\sqrt[3]{5^3}+4\sqrt[3]{2^6}\right)

We can simplify the cube roots now, since for any
x we have
\sqrt[3]{x^3}=x. So


=\sqrt[3]5\left(2\cdot2+3\cdot5+4\cdot2^2\right)


=\sqrt[3]5\left(4+15+16\right)


=35\sqrt[3]5

answered
User Atypical
by
8.6k points

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