y=9x-1, x+2y=17
solve by substitution
1) y = 9x - 1
2) x + 2y = 17
Equation 1 already gives us a value for y,
which we can substitute into equation 2.
x + 2y = 17
x + 2(9x - 1) = 17
x + 18x - 2 = 17
19x -2 = 17
19x - 2 + 2 = 17 + 2
19x = 19
19x / 19 = 19 / 19
x = 1
Using equation 1, we can solve for y.
y = 9x - 1
y = 9(1) - 1
y = 9 - 1
y = 8
Put both of those values into equation 2 to check the answers.
x + 2y = 17
1 + 2(8) = 17
1 + 16 = 17
17 = 17