Add. Simplify if possible.

Question

7/9z^3 + 1/21z^3

I came up with 49+3z/63z^3

Is this correct?

Answer 1

We have this:

7/9z^3 + 1/21z^3

Our LCD is 63z^3.

We now divide the LCD by each denominator and then multiply the quotient by each numerator.

63z^3/9z^3 = 7

Then, 7 times 7 = 49

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Next fraction:

63z^3 divided by 21z^3 = 3

Then, 3 x 1 = 3

We now add the numerators and keep the LCD.

(49 + 3)/63z^2

Final answer: 52/63z^3

Done!

Answer 2

Thanks Guido.