Question

4. Solve using the substitution method. Show your work. If the system has no solution or an infinite number of solutions, state this.
18x + 6y = 78
12x + 54y = -48

Answer 1

i got 30x+60y=22

Answer 2

Give me a few min. - I'm working on it.......

Answer 3

(18x + 6y = 78)/6
3x + y = 13

(12x + 54y = -48)/6
2x +9y = -8



3x + y = 13
2x +9y = -8

Answer 4

those are equavialent and easier equations to work with

Answer 5

it asking you what value for x and y make the system consistent

from the first eq we can say that: y = 13-3x and substitute that "almost" value into the second eq and solve that for x

Answer 6

2x +9y = -8

2x +9(13-3x) = -8

2x +9(13) -27x = -8

2x -27x = -8 -9(13)

-25x = -8 -9(13)

x = \(\cfrac{-8-9(13)}{-25}\) = \(\cfrac{125}{25}\)=5

Answer 7

since x = 5, if i did it right, we can solve for y now

y = 13 - 3x

y = 13 - 3(5)

y = 13 - 15 = -2

Answer 8

its always good to dbl chk the results since head math is rife with error

Answer 9

ok

Answer 10

18x + 6y = 78
5 -2
90 - 12 = 78 .... good

12x + 54y = -48
5 -2
60 - 108 = -48 .... good

Answer 11

@amistre64 - Could you please check the answer I got on my last question - I am still confused with the answer I got, thanks :)