Question

How do I find these equations using substitution y=-3x+5 and 5x-4y=-3 ?

Answer 1

(1,2)

Explanation:

1) To solve using substitution, first isolate one of the variables in one of the equations. However, the y in y = -3x + 5 has already been isolated, so we don't need this step. Instead, take that value of y and substitute it for the y in the other equation, 5x - 4y = -3. So, substitute -3x + 5 for the y in 5x - 4y = -3 and solve:

`5x-4(-3x+5)= -3\\5x+12x-20=-3\\17x-20=-3\\17x = 17\\x = 1`

2) So, x = 1. Now, take that value of x and substitute back into any of the equations to find the y value. (I chose to substitute it into y = -3x + 5, but either choice is fine). So, substitute 1 for the x in y = -3x + 5 and solve:

`y = -3(1)+5\\y = -3+5\\y = 2`

So, y = 2. Thus, by knowing both x and y values, the solution would be (1,2).

Answer 2

x=1

Explanation:

you would change it to 5x-4(-3x+5)=-3, because you put the info for the first equation into the second equation.

5x-4(-3x+5)=-3

5x+12x-20=-3

17x-20=-3

17x=17

x=1