Question

which is the sum of the solutions, x + y, for the systems of linear equations
7x + 3y = -12
2x + 5y = 38

Answer 1

go help that guy with the ellipse!

Answer 2

after i complete the square conics make me dizzy

Answer 3

wut?

Answer 4

sorry

Answer 5

lets do this mulitiply the top equation by -5, bottom by 3 and see what we get

Answer 6

\[-35x-15y=60\]
\[6x+15y=114\]

Answer 7

check my arithmetic but i think it is right. now add to get
\[-29x=174\]

Answer 8

making \[x=\frac{174}{-29}=-6\]

Answer 9

if x = -6 then the first equation give
\[-42+3y=-12\]
\[3y=30\]
\[y=10\]

Answer 10

wait slow down down after i get -29x = 174, where do i go from there and remember im not good at math so use easy words

Answer 11

so the sum is 10-6=4

Answer 12

was it clear how to get -29x=174? because that is all the work

Answer 13

yah but aftr that im confused

Answer 14

ok that was the hard part. the easy part is this: if
\[-29x=174\] then this is a one step equation to solve. to get x by itself divide both sides by -29

Answer 15

the -29 will cancel on the left, leaving x by itself, and on the right you get whatever
174/-29 is

Answer 16

i used a calculator

Answer 17

was that part ok?

Answer 18

yes

Answer 19

ok so now we know that x = -6 because that is what i got from 174/-29

Answer 20

now i take the -6 and substitute it in to either of your first two equations for x

Answer 21

you can use either equation. i chose the first one. where i saw an x i put a -6

Answer 22

it was
\[7x + 3y = -12\]

Answer 23

so i replace x by -6 and get
\[7\times -6+3y=-12\]

Answer 24

ok so if the final ans is 4 then i know how to to do it

Answer 25

i am not done yet. i need x which is -6. then i need y so i have to solve the above equation for y

Answer 26

\[-42+3y=-12\]
\[3y=-12+42\]
\[3y=30\]
\[y=\frac{30}{3}\]
\[y=10\]

Answer 27

right!
x+y=-6+10=4
gj satellite

Answer 28

now i know x = -6 and i know y = 10 so i know that x+y is -6+10=4

Answer 29

yay i got it