Major Help Required with ( substitution, elimination) Everyone Can contribute by doing one of the problems .?

Question

Solve everyone of these problem using a method of choice, verify each solution, if the problem does not submit exactly to the solution is it because it submits an infinity or not?
( substitution, elimination)...

Everyone Can contribute by doing one of the problems so it can be completed.




A)

5x - 3y =9
2x - 5y = -4

B)

3a + b - 4 =0
2a - 10 =3b

C)

x=2-2y
y+1/2x= -1

D)

x/3+y/4= -1
2x+y= -8

E)

3p - 6q=0
4p+q=3

F)

2x+3y= -2
8x+5y= -6

G)

0,2x + 0,7y=1,5
0,3x - 0,2y = 1

H)

x/5 + y/3 = 3
x/2 - y/12 = 2

I)

2(m+1) - (n - 4) = 15
3(m-1) + 4(n+2) = 2

Answer 1

A)

5x - 3y =9 (1) *2
2x - 5y = -4 (2) *-5
10x-6y=18
-10x+25y=20
adding
19y=38
dividing by 19
y=2
subs in (1)
5x-6=9
adding 6
5x=15
dividing by 5
x=3
so solution set{3,2}

B)

3a + b - 4 =0 (1)
2a - 10 =3b (2)
from (1) adding -3a+4
b=-3a+4
subs in (2)
2a-10=3(-3a+4)
2a-10=-9a+12
adding 9a+12
11a=22
dividing by 11
a=2
sub in b=-31+4
b=-2
so the solution set={2,-2}


C)

x=2-2y
y+1/2x= -1
substituting x=2-2y in (2)
y+(1/2)(2-2y)=-1
simplifying
y+1-y=-1
cannot be solved


D)

x/3+y/4= -1 (1)
2x+y= -8 (2) (1)*12
4x+3y=-12 (2)*-3
-6x-3y=24
adding
-2x=12
dividing by -2
x=-6
substituting in 2x+y=-8
-12+y=-8
adding 12
y=4
solution set={-6,4}


E)

3p - 6q=0 (1)
4p+q=3 (2)*6
24p+6q=18
adding to (1)
27p=18
dividing by 27
p=2/3
subsin (1)
2-6q=0
adding -2
-6q=-2
dividing by -6
q=1/3
solution set={2/3,1/3}

F)

2x+3y= -2 (1)*-4
8x+5y= -6 (2)
-8x-12y=8
adding to (2)
-7y=2
dividing by -7
y=-2/7
substituting in
2x+3y=-2
2x-6/7=-14/7
adding6/7
2x=-8/7
dividing by 2
x=-4/7
the solution set{-4/7,-2/7}
G)

0,2x + 0,7y=1,5 *10 =2x+7y=15 *3
0,3x - 0,2y = 1 *10 =3x-2y=10 *-2
6x+21y=45
-6x+4y=-20
adding
31y=25
y=25/31
3x-50/31=310/31
adding 50/31
3x=360/31
dividing by 3
x=120/31

H)

x/5 + y/3 = 3 (1)*15 3x+5y=45*-2
x/2 - y/12 = 2 (2)*12 6x-y=24
-6x-10y=-90
6x-y=24
adding -11y=-66
dividing by -11
y=6
substituting in 3x+5y=45
3x+30=45
adding -30
3x=15
dividing by 3
x=5

I)

2(m+1) - (n - 4) = 15
2m+2-n+4=15
2m-n=9 (1)
3(m-1) + 4(n+2) = 2
3m-3+4n+8=2
3m+4n=-3 (2)
8m-4n=36 2m-n=9 (1) *4
adding
11m=33
dividing by 11
m=3
substituting in 2m-n=9
6-n=9
adding -6
-n=-3
n=3
so solution set {3,3}

Answer 2

Elimination: 12x-3y=27 {multiply both sides by 3} 2x+3y=27 14x=0 {add the two equations} x=0 4(0)-y=9 {substitution} -y=9 {simplify} y=-9 2(0)+3(-9) = -27 {substitution} -27 =-27 {simplify} Substitution: 4x-y=9 -y=9-4x {subtract 4x from both sides} y=-9+4x {divide by -1} 2x+3(-9+4x) = -27 {substitute} 14x-27 = -27 (simplify and combine like terms} 14x=0 {add 27 to both sides} x=0 4(0)-y = 9 {substitute} -y = 9 {simplify} y = -9 So X = 0 and Y = -9...personally, I've always found elimination to be the easier was unless you have a positive single variable (so just X or Y) in an equation.

Answer 3

I'll answer A for you, and then you're on your own.

5x - 3y = 9 → 10x - 6y = 18
2x - 5y = -4 → 10x - 25y = -20

subtracting, 19y = 38, so y = 2
subbing back in,
5x - 3(2) = 9
5x = 15
x = 3

But the others are right. This is a cheap attempt to get your homework done for you, not a sincere effort to learn. I've flunked hundreds like you. Wise up.

Answer 4

I think the purpose of this place is to provide a person with guidance when they are stuck, enough so they can go back and complete the rest of the problems of this nature themselves. You do realize when the test comes, if you don't do this now, you will have no idea how to even begin, and your instructor might get the idea you never actually worked the homework problems yourself. Not to mention how poorly you'll do on your exams, and future lessons since math, like many other things, is built on an accumulation of past knowedge. If you fail to learn one skill, you will not go any further without running into problems.
Have you even tried "ONE" of these problems yourself? Post your work, then we can guide you.

Answer 5

Normally, when I read people saying "do your own homework!" I try and not make assumptions of people asking the questions. In some of the cases it is ambiguous whether the asker is truly asking for help.

In this case, it's so blatantly obvious. I'm sorry but I can't help someone who doesn't want to be helped.

Answer 6

for B) a=2 and b=-2. if you think this is the correct answer i can work for the others

Answer 7

Do your own homework!
If you don't learn this method now, you are going to have major problems later on!

Answer 8

What time is it where Philo and Puggy are, and why aren't they asleep? It's 3AM Eastern time.