Question

Solve the equation using the addition method
(fraction) 15/7 x + 5y = -5
3x + 7y = -7

Answer 1

\(\large\color{slate}{ \frac{\LARGE 15}{\LARGE 7} x + 5y = -5 }\)

\(\large\color{slate}{ 3x + 7y = -7 }\)

1) Divide the first equation by 5.
2) multiply the first equation times -7.
3) add the equations.
(this is going to eliminate the y for you

Answer 2

so what is 15/7 divided by 5?

Answer 3

i just get a long decimal

Answer 4

@SolomonZelman ????

Answer 5

15 / 5 =?

Answer 6

3

Answer 7

so 3/7?

Answer 8

yes, if you divide 15/7 by 5 you get 3/7

Answer 9

ok

Answer 10

so your new first equation, after dividing it by 5 will be?

Answer 11

so it would be
3/7 + y = -1 divide that by -7 and it's....

Answer 12

? + -7y = 7

Answer 13

3/7 divided by -7 is____?

Answer 14

@SolomonZelman ?

Answer 15

you get after dividing by 5,
3/7 x + y = -1

now mltiply times -7

Answer 16

3 + -7y = 7

Answer 17

now what?

Answer 18

3/7 * -7 = -3
1 * -7 = -7
-1 * -7 = 7

So,

3/7 x * -7 = -3x
y * -7 = -7y
-1 * -7 = 7

So your 1st equation would now be: \(\large\color{teal}{ -3x - 7y = 7 }\)

\(\large\color{teal}{ 3x + 7y = -7 }\)

Answer 19

Ok, what do I do once I have the first equation?

Answer 20

if you have multiplied the first equation times 7, instead of multiplying times -7, then it would be: \(\large\color{teal}{ 3x + 7y = -7 }\)

and your second equation as it was, is, \(\large\color{teal}{ 3x + 7y = -7 }\)

Answer 21

both equations are same, no?

Answer 22

so the answer is just 3x + 7y = -7? I need two numbers in a ( , ) thingy

Answer 23

when two equations are same, the have infinite solutions.

Answer 24

Ohhh ok. Thank you so much for the help! :)

Answer 25

sure