Remark
The upper answer is correct. Any time you are dealing with addition or subtraction and one of the numbers is irreducible and remains irrational no matter what you do, then the entire addition or subtraction of terms remains irrational.
For the second one that you did not answer, it works the same way as the comment says.
3√2 * 8√18 give two numbers that can be multiplied under the square root sign.
3*8 = 24
√(2*18) = √(36) = 6
The answer is 24*6 = 144
This procedure is the only way I know that you can get a rational result from two irrational factors. In fact it is really quite useful to know. You will use this when you learn how to rationalize the denominator. This exact method is used to do that.
let's firstly, convert the mixed fraction to improper fraction, and then subtract.
![\bf \stackrel{mixed}{2\frac{3}{4}}\implies \cfrac{2\cdot 4+3}{4}\implies \stackrel{improper}{\cfrac{11}{4}} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \cfrac{11}{4}-\cfrac{2}{3}\implies \stackrel{\textit{our LCD will be 12}}{\cfrac{(3)11-(4)2}{12}}\implies \cfrac{33-8}{12}\implies \cfrac{25}{12}\implies 2\frac{1}{12}](https://tex.z-dn.net/?f=%5Cbf%20%5Cstackrel%7Bmixed%7D%7B2%5Cfrac%7B3%7D%7B4%7D%7D%5Cimplies%20%5Ccfrac%7B2%5Ccdot%204%2B3%7D%7B4%7D%5Cimplies%20%5Cstackrel%7Bimproper%7D%7B%5Ccfrac%7B11%7D%7B4%7D%7D%0A%5C%5C%5C%5C%5B-0.35em%5D%0A%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%0A%5Ccfrac%7B11%7D%7B4%7D-%5Ccfrac%7B2%7D%7B3%7D%5Cimplies%20%5Cstackrel%7B%5Ctextit%7Bour%20LCD%20will%20be%2012%7D%7D%7B%5Ccfrac%7B%283%2911-%284%292%7D%7B12%7D%7D%5Cimplies%20%5Ccfrac%7B33-8%7D%7B12%7D%5Cimplies%20%5Ccfrac%7B25%7D%7B12%7D%5Cimplies%202%5Cfrac%7B1%7D%7B12%7D)
Y = 5x because 5 times the x number ( for ex. 12) is equal to the y number (60)
Answer: 523.60
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Work Shown:
V = (4/3)*pi*r^3
V = (4/3)*pi*5^3
V = 523.598775598299 <<-- use a calculator for this step
V = 523.60 <<-- rounding to two decimal places
Good evening :)
4 3/4 * 5 3/8
= 19/4 * 43/8
=Multiply numerator together and denominator together
= 817/32
I hope that's help !
