let's firstly convert the mixed fractions to improper fractions and then add, bearing in mind that the LCD from 8 and 4 is simply 8.
![\bf \stackrel{mixed}{5\frac{7}{8}}\implies \cfrac{5\cdot 8+7}{8}\implies \stackrel{improper}{\cfrac{47}{8}} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{47}{8}+\cfrac{11}{4}\implies \stackrel{\textit{using the LCD of 8}}{\cfrac{(1)47~~-~~(2)11}{8}}\implies \cfrac{47-22}{8}\implies \cfrac{25}{8}\implies 3\frac{1}{8}](https://tex.z-dn.net/?f=%5Cbf%20%5Cstackrel%7Bmixed%7D%7B5%5Cfrac%7B7%7D%7B8%7D%7D%5Cimplies%20%5Ccfrac%7B5%5Ccdot%208%2B7%7D%7B8%7D%5Cimplies%20%5Cstackrel%7Bimproper%7D%7B%5Ccfrac%7B47%7D%7B8%7D%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20%5Ccfrac%7B47%7D%7B8%7D%2B%5Ccfrac%7B11%7D%7B4%7D%5Cimplies%20%5Cstackrel%7B%5Ctextit%7Busing%20the%20LCD%20of%208%7D%7D%7B%5Ccfrac%7B%281%2947~~-~~%282%2911%7D%7B8%7D%7D%5Cimplies%20%5Ccfrac%7B47-22%7D%7B8%7D%5Cimplies%20%5Ccfrac%7B25%7D%7B8%7D%5Cimplies%203%5Cfrac%7B1%7D%7B8%7D)
The answer is the first one
The product of something means multiplying the terms together.
(2x+3) (4x^2-5x+6)
Secondly you need to distribute the terms to each other (Think of problems like FOIL)
2x * 4x^2 + 2x(-5x) + 2x * 6 + 3 * 4x^2 + 3(-5x) + 3 * 6
Then you must take into account that some of the numbers are negative. (minus-plus rules!)
2x * 4x^2 - 2x * 5x + 2x * 6 + 3 * 4x^2 - 3 * 5x + 3 * 6
Now is the tricky part of simplifying everything.
2x * 4x^2 = 8x^3
2x * 5x = 10x^2
2x * 6 = 12x
3 * 4x^2 = 12x^2
3 * 5x = 15x
3 * 6 = 18
8x^3 - 10x^2 + 12x + 12x^2 - 15x + 18
Then you group like terms.
8x^3 - 10x^2 + 12x^2 - 3x + 18
8x^2 + 2x^2 - 3x + 18
The trickiest part of this is distributing all of the terms within the parentheses, once you've done that, it's smooth sailing!
Replace each "x" in the original equation with (4):
3(4)^2 + 2(4) - 5
= 3(16) + 8 - 5 = 48 + 8 - 5. Can you finish this?
