Need help on math desperately!

[KLDG]

I have no idea what i'm doing when it comes to math besides the basic multiplications and division etc...if anyone can help me with this, as it is my college work i need to turn in before 2 days!

1. Solve the following systems of equations by graphing and state the solution.
x+y=1
3x-4y=10


2. Solve the following systems of equations using the addition/elimination method.

a. x+2y=-15 b. 2x-2y=6
3x-2y=3 -3x-5y=15



3. Solve the following systems of equaions using the substitution method.

a. 3x+2y=10 b. x-4y=5
y=6-x x=19-3y


4. A rancher wants to spread a 300-lb grass seed mixture that is 50% tall fescue. If the rancher has on hand a seed mixture that is 80% tall fescue and a mixture that is 20% tall fescue, how many pounds of each mixture are needed to make 300 lbs of the 50% mixture?



Please try to help me with this as i need it to pass the class for the year and im really busy study for my ccna final.

 

[Determinate]

1. Solve the following systems of equations by graphing and state the solution.
x+y=1
3x-4y=10

set them equal to y:
y = 1 - x
-4y = -3x + 10, y = (3/4)x - (10/4)

y = y, and so you can set them equal to each other and plot.

2. Solve the following systems of equations using the addition/elimination method.

a. x+2y=-15 b. 2x-2y=6
3x-2y=3 -3x-5y=15

Dunno what addition/elimination method is, but I'm guessing this is what you gotta do:
a. x + 2y = - 15
3x - 2y = 3; 2y - 2y = 0

x = -15
3x = 3

4x = -12
x = -3

(-3) + 2y = - 15
2y = -18
y = -9

b. 2x - 2y = 6
-3x - 5y = 15

-3(2x - 2y = 6) = -6x + 6y = - 18
-2(-3x - 5y = 15) = 6x + 10y = -30; -6x+6x = 0

6y = - 18
10y = - 30

16y = -48
y = - 4

2x - 2(-4) = 6, 2x +8 = 6, 2x = -2, x = -1

3. Solve the following systems of equaions using the substitution method.

a. 3x+2y=10 b. x-4y=5
y=6-x x=19-3y

a.
3x + 2(6-x) = 10
3x +12 -2x = 10
x + 12 = 10
x = -2

y = 6 - x
y = 6 + 2
y = 8

b.
(19 - 3y) - 4y = 5
19 - 7y = 5
14 = 7y
y = 2

x = 19 - 3y
x = 19 - 3(2), x = 19 - 6
x = 13

 

[KLDG]

I really love you....

 

[sheymyster]

Hey man, no offence or anything Determinate, I see you on here alot and you are very intelligent, but I believe you may have done the substitution/elimination problem incorrectly. When I substitute your answers into the original equatiosn (x=-3, y=-6) they do not equal the values they should (-15 and 3). I will try and explain the elimination technique below, but it has been awhile so forgive me if its hard to understand, lol.

So when you are eliminating you are simply trying to get one of the variables in the two equations you are given to cancel out when you add the equations together, so that you are just left with one variable, which can easily be solved for. In your case you have:

Equation 1: x + 2y = -15
Equation 2: 3x - 2y = 3

They have been nice to you and have given you two equations that already cancel when added, so if you add the equations together, you get 3x + x which is 4x, 2y - 2y which is 0 (this is the canceled variable), and -15 + 3 which is -12. Now your new combined equation is as follows

4x = -12 when you solve for x you should come upon [x = -3]

Now that you have obtained x, there is no need to eliminate again to find y, you can simply substitute in your acquired x value into one of your given equations, leaving only one variable, y, and solve for it normally.

so if x = -3, then the equation x + 2y = -15 becomes (-3) + 2y = -15
After some algebra, your solution should be [y = -6]

To test our answers, just simply input the x and y values into both of the original equations to ensure there aren't any discrepencies.

(-3) + 2(-6) = -15 This one is correct!
3(-3) - 2(-6) = 3 This one also matches!

Okey dokey, so the values we found work, hope it helped man!

 

[Determinate]

Yea you're right. I added incorrectly.

I did -3 + 2y = -15, 2y = -18

there was my error. I disregarded the negative on the three.
It should have actually been solved as

-3 + 2y = -15
2y = -12
y = -6

so thanks for that, Sheymyster.

 

[sheymyster]

no problem bro, actually didn't know sythe even had this section or all of the others til recently, I think its really cool that a gaming site has a homework help section, props for having IRL sections, LOL. I will be throwing up some of my organic stuff on here soon!