Question

Please help!!! Have been stuck on this problem for the past hour. can someone be so kind and explain it to me. I have a Quiz tomorrow on this. solving systems using substitution y = - 7y + 3; Y+ 7x = 10

Answer 1

Your starting equations are

y = -7y + 3 and
y + 7x = 10, is that correct? The previous response has an x in the first sentence, so I wanted to ask.


y = -7y + 3 simplified is
8y = 3
y = 3/8 (0.375 as a decimal)

If we sub 0.375 for y in the second equation, we can solve for x.

y + 7x = 10
0.375 + 7x = 10
7x = 9.625
x = 1.375

So y = 0.375 and x = 1.375

Checking the solution:
0.375 + 7(1.375)
= 0.375 + 9.625 = 10

and 0.375 = -7(0.375) + 3
0.375 = -2.625 + 3
0.375 = 0.375

Answer 2

Explanation:

y = -7x+3

substitute -7x+3 for y in the other equation.

y + 7x = 10

(-7x+3) + 7x = 10

3 = 10, a contradiction, so there is no solution.

If you were to graph both equations, you would see that they are parallel lines. There is no point that belongs to both lines, so there is no (x,y) that satisfies both equations.