Math question..

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dg101

Active member
hey guys, im doing my math homework and im fucked for this one question. It seems so simple, its the easiest one on the page but i cant figure it out.

"Find the value of Y if X+Y+Z=25, X=Y=19 and Y+Z=18"

If you can figure it out let me know how you did it, because I need to show work. if you can help, thatd be great
 
^ thats what i got. this is gonna be hard to explain online but you have to solve for one term, i solved in terms of x then plugged the values in.

first set these = to y

x+y=19 , y+z=18 -> y=19-x , y=18-z

then set them equal to each other

19-x=18-z -> 1=x-z -> z=x-1

to get x use the above y=19-x -> x=19-y

now plug all this into the equation:

x+y+z=25

19-y + 19-x + x-1 =25

plug in the value you set for y again

19-(19-x) + 19-x + x-1 =25

you'll see the 19's and 2 x's cancel and your left with x=7 now plug that into the above x+y=19 equation and you see y=12

that might be more complicated than needed but thats how i did it
 
Just do a substition... that is if you have three variables, isolate one (you'll have a variable on the other side) and replace the expression on the other side in another one you have. You'll end up being able to isolate one, and then all you have to do is put it in another and isolate again, till you have all three.

I re-read that and it becomes clear it's a little hard to make math understandable on NS.
 
gr 10, im not a dumbass either, im getting 87 in enriched math 10.. for some reason i just couldnt get this one. thanks for the explanation dragons986, it helped.
 
no problem glad it helped. im going towards a mechanical engineering major and assuming i make it through my next 2 or possibly 3 years of college ill automatically have a math minor with my engineering major. oh joy. good to know i can still do 10th grade math haha.
 
Sounds awesome, good luck with your studies. Ive got another a few more for ya if you have time. (^ means to the power of, just in case you didnt know)

first one..

"If N=(7^P+4)(5^Q)(2^3) is a perfect cube, where P and Q are positive integers, what is the smallest possible value of P+Q?"

This ones multiple choice, the easiest way would be to work backwards, but she wants us to show the work, so an explanation would be great. Possible answers are 5,2,8,6 or 12.

second one..

"What is the number of solutions (x,y) for the equation 3X+Y=100, where X and Y are positive integers?"

The last one is probably simple, I just dont understand what the question is asking for.

"A teacher has more than 25 students in his class. He has more than 2 but less than 10 boys and more than 14 but less than 23 girls in his class. How many different class sizes would satisfy these conditions?"

Thats the question word for word.. I dont understand it. The multiple choice answers are 5,6,7,3,4. It would be great if you could explain as well, id like to learn how to do this.

If you get around to doing them, thanks alot. These weekend assignments are basically random questions to challenge us that have nothing to do with what we are studying, so some of them are confusing.
 
nevermind, I worked them out.

for the first one i got 5, because the exponent of 7 would have to be a multiple of 3.. so P is 2. the exponent of 5 is 3 because 125 is the cube of 5. 2^3 is already a cube. 3+2=5

For the second one i just worked out the ranges, i got 33

The last one i talked to my buddy, he was fuckin clueless too but he understood wut the question asked, so i was able to work it out by finding the range
 
sweet you learned algebra in 2nd grade, i cant imagine what kind of mind blowing stuff your doing now if your in or graduated high school.
 
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