Good mathematicians here?

Hola duders. I'm currently studying economy, and one of my subjects is math. I've a deadline by friday to turn in a home test. I was wondering if anyone here could help me out a little with a few of the problems. I've completed and proof read over half of the paper, but there are a few things that seem to elude me. I'll just post a couple of the problems here, and if you could help me out, I'd appreciate it a lot.

Okay guys. Would love to get some help with these. Thanks a bunch in advance.

Here you go, handwriting isn't great though,

I would double check these for mistakes if I were you, also I'm not sure what you need to do for the last two, simplify them? Also make sure you do understand them, as someone who once fell down the well of "I'll just copy it now and understand later" it never ends well. If you have any questions feel free to ask.

(First pic I accidentally wrote 35y and then 38y I meant 35x and 38x)

Er, are you even allowed to ask for help on the test, what is it specifically asking you to do with each set of equations, and what exactly are you not understanding on each problem? I mean, I can guess, but I'd rather not do all the work.

So the top are simultaneous equations [worksheet]

The middle ones are quadratic roots (cross multiply out b first) [worksheet]

I think the last one needs to be refactored before solving (I may be somewhat rusty*).

* Kids: if you do something (major in it) at Uni, don't spend the next decade letting that knowledge atrophy as you focus on other subjects. Try to keep on top of what you learned via occasional refreshers.

For question c I got X = 2.375 and Y = 7.625

http://i.imgur.com/stoE3l9.jpg

What have you tried? If you only want to verify your results then try wolframalpha.com.

(Asking for complete solutions is not helping you.)

@officialjack: from step 2 to 3, adding the two equations does not cancel the 21x, you need to minus one from the other

Ok, just read the problems. Since you already have the answers for the first two sets I'll just point out something about the third set. Guessing that the prompt is to simplify them, they seem to be testing very specific equations that you probably should have memorised. One is (a+b)^2 = a^2+2ab+b^2, the other is a^2-b^2=(a+b)(a-b). Knowing that, it should be pretty simple to simplify them. (by the way, I'm honestly surprised I still remember these after years of never using them lol)

Okay guys. Thanks for the help! Just to clarify: I've tried to solve the problems, but I just needed to double check the answers, and take a look at how it's supposed to be done compared to how I've done it. And that's a good thing, cause when seeing this, I've certainly made mistakes in a couple of the problems.

Also, the text in the problems are as follows: Solve the equation systems, solve the equations, and add up and simplify.

OK I'm guessing for the last two questions they just want you to simplify them so here they are.

b. is easy, just expand and simplify

c. not as easy. you have to notice that the bottom of the first fraction is a difference of 2 squares and so can be written as

(a+b)(a-b) which you can use as the lowest common factor for all three fractions.

Hope that makes sense.

Khan Academy is really great for learning maths topics, I suggest you check it out whenever you're doubting your understanding of a subject.