<p>I don't know why I'm having so much trouble with this problem but if ANYONE could help me, I would really appeciate it:</p>
<p>Sam can do a job in x hours. Denise can do the same job in x + 2 hours. How long will it take Sam and Denise to do the job together? (Express your answer in terms of X)?????</p>
<p>Is the answer 5/8x</p>
<p>the answer is x^2+2x/2x+2 but I’m getting the inverse of that…</p>
<p>Ah yes… That’s essentially what i got but i plugged in numbers for x so that’s where the 5/8 came from.</p>
<p>Here I’ll explain:</p>
<p>The reason you are getting the inverse is that 2x+2/x^2+2x is the fraction of the job you can do in one hour. But to do the whole job, you have to take the inverse. Does that make sense?</p>
<p>I skipped all the unnecessary calculations that come before taking the inverse b/c it seems like you understand those.</p>
<p>So it’s like 2x+2/x^2+2x of the job/ in one hour.
So what’s the whole job?
The inverse is the answer, which is the WHOLE JOB</p>
<p>I know the job that they do together is 1/x but the odd thing is that doing this with a different technique (than taking the inverse) gives a completely different answer, but I think that’s because I’m not using numbers, so thanks, I think I just made it more complicated for myself</p>
<p>I can also show all the steps to you algeabraically if you’d like?</p>
<p>And no the job that they do together is not 1/x.
It’s 2x+2/x^2+2x of the job/in one hour. THAT’s THE RATE AT WHICH THEY DO THE JOB TOGETHER.</p>
<p>No what I meant was that you have 1/x=2x+2/x^2+2x and then you take the inverse to get to the answer. Correct?</p>
<p>More of the same type of questions:</p>
<p><a href=“http://talk.collegeconfidential.com/sat-preparation/819254-can-someone-plz-solve-these-sat-math-questions.html[/url]”>http://talk.collegeconfidential.com/sat-preparation/819254-can-someone-plz-solve-these-sat-math-questions.html</a></p>
<p>See Post 5 by THE Turtle!</p>
<p>"4)Sam can do a job in x hours. Denise can do the same job in x+2 hrs. how long will it take Sam and Denise to do the job together?</p>
<p>answer= (x^2+2x)/(2x+2)"</p>
<p>Sam can do 1/x of the job per hour. Denise can do 1/(x+2) of the job per hour. By adding these expressions, we get, in terms of x, how much they can do per hour: </p>
<p>1/x + 1/(x+2) = (2x+2)/(x^2+2x). (Make sure you find a common denominator when solving this.)</p>
<p>To get how long it will take them, we take the reciprocal of the above, which yields: (x^2+2x)/(2x+2).</p>
<p>but if it’s wrong I would appreciate it if you did it algebraically</p>
<p>^oh i see what you’re saying. And i guesssss you could do it that way. Refer to post 12, which is essentially what i was trying to communicate.</p>
<p>yes thank you, I see what you were doing. You did it without making it into an equation but just expressions, got ya.</p>
<p>^exactly…</p>
<p>This becomes an easy problem when you plug in.</p>
<p>Sam can do a job in x hours. Denise can do the same job in x + 2 hours. How long will it take Sam and Denise to do the job together? (Express your answer in terms of X)??? </p>
<p>Let’s say sam can do a job in 4 hours (x=4). Denise does the same job in 6 (4+ 2=6). The job is 24 (I randomly plugged in a multiple of 4 and 6. Say it’s making 24 baskets.)</p>
<p>Using the number, Sam’s rate is 6/hr. Denise’s rate is 4/hr. Ergo the combined rate is 10/hr. How long does it take them to do the job together? 24/10 = 2.4 </p>
<p>Plug 4 into x in the answer choices until you get 2.4.</p>
<p>While this may sound like a lot of calculating, it makes much more sense to students.</p>
<p>there’s also an equation for problems like these. t stands for time. t1 x t2 / t1 + t2</p>
<p>
</p>
<p>Is it me or does xiggi seem a little jealous? :p</p>
<p>Hahaha, JK!!</p>
<p>here is my method of doing those kind of job problems.
Work=Power times Time spent
Lets assume that total work is 1
Power=Work/Time Spent
S’s Power 1/(x)
D’s Power 1/(x+2)
S and D’s combined Power 1/(x)+1/(x+2)=(2x+2)/(x^2+2x)
Time Spent=Work/Power
Time spent=1/ (2x+2)/(x^2+2x)=(x^2+2x)/(2x+2)</p>