Systems of equations?

Question

I can't get the answer to this problem! well, i know how to do it, but the numbers are weird and my online hw program says it's wrong! I tried 2 diff answers and only have one try left. Help!

Solve this systems of equations by substitution:
3x+5y = -19
2x+7y= -31

it's not y = (131/11) and x = (-288/11) or ugly numbers like that cuz i input those and it was incorrect..but did anyone else get that?? thanks!

Answer 1

use elimination; multiply first equation by 2 and second equation by -3

6x+10y=-38
-6x-21y=93

add them together
-11y=55
y=-5

substitute y=-5 into one of the original equations,
3x+5(-5)=-19
3x-25=-19
3x=6
x=2

Answer 2

3x+5y=-19
or.3x= -19-5y
or,x= -(5y+19)/3
substituting this value of x in the equation
2x+7y= -31,we get
-2(5y+19)/3 +7y= -31
or-2(5y+19) +21y= -93 [multiplying both sides by 3]
or,-10y-38+21y= -93
or,11y= -93+38= -55
or y=-55/11= -5
Putting the value ofy in the first equation
3x+5y= -19.we get
3x-25= -19
or,3x= -19+25=6
or x=6/3=2
Hence x=2 and y= -5

Answer 3

Solve first eq. for x -

3x = -19 - 5y

x = -19/3 - 5y/3

Now plug in-

2(-19/3 - 5y/3) + 7y = -31 ==

-38/3 - 10y/3 + 7y = -31 ==

-38/3 + 11y /3 = -31 ==

11y/3 = -93/3 + 38/3 = -55/3 ==

11y = -55 ==

y = -5

Now solve for x -

3x + 5(-5) = -19 ==

3x - 25 = -19 ==

3x = 6

x = 2

.

Answer 4

3x+5y = -19
2x+7y= -31

About your answer... it sounds as if you might have lost a denominator early in your substitution... just a thought... when things seem to go really sour, it's sometimes something simple like that.

Solve for one of the variables in one of the equations
I’ll solve the first equation for y
3x+5y = -19
Add -3x to both sides…
5y=-19-3x
Multiply both sides by 1/5
y= -(3x+19)/5

Now, substitute that into the other equation…
2x+7y= -31
2x - 7(3x+19)/5=-31

Multiplying both sides by 5
10x - 7(3x+19) = -155

Distributing, and doing a little arithmetic…
10x -21x -133 = -155

Distributing again
-11x-133=-155

Adding 133 to both sides
-11x=-22

Multiplying both sides by -1/11
x = 2

Plug that value into either equation to get y…
2x+7y=-31
2(2)+7y=-31
4+7y=-31

Add-4 to both sides
7y = -35

Multiply both sides by 1/7
y = -5

Answer 5

the place to commence is to discover the thank you to combine the two equations into one ideally removing between the unknowns interior the technique. So: x-y=3 may be rearranged to x=3+y Substituting this into the 1st equation supplies (3+y)squared + y squared = 29 resolve this to get a solution for y then replace this extensive style for y interior the 2nd equation and resolve to get x. answer: y = 2 x = 5

Answer 6

3x=-19-5y
x=(-19-5y)/3
{2(-19-5y)}/3+7y=-31
-38-10y+21y=-93 (miltiply both sides by 3)
when you bring -38 to other side its
-93+38 ( not 131)


11y=-55
y=-5

3x = -19-5*-5
3x = -19+25
x = 2

Answer 7

Y=-5
X=2

Answer 8

3x + 5y = - 19-----X by - 2
2x + 7y = - 31-----X by 3

-6x - 10y = 38
6x + 21y = - 93-----ADD

11y = - 55
y = - 5

2x - 35 = - 31
2x = 4
x = 2

Solution is x = 2 , y = - 5

Answer 9

x = 2
y = -5

Answer 10

x=2
y= -5
hope this helps :)