A line passing through (7, 17) and (8, y) is parallel to a line with slope –9. What is the value of y?
Find the slope and y-intercept.
x + 2y = –6
2007-02-22 13:59:28 · 4 answers · asked by Michelle P 1 in Science & Mathematics ➔ Mathematics
change in Y / change in X = -9
y-17 / 1 = -9....so.....y=8
X+2Y=-6. re-write in Y = mX +b form
2Y = -X -6
Y = -1/2 X -3....so....slope is -1/2 and y-intercept is -3
2007-02-22 14:05:40 · answer #1 · answered by davidosterberg1 6 · 0⤊ 0⤋
If the lines are parallel, then m (the gradient) is same for both.
dx/dy=m: implying; (8-7)/(y-17) = -9: you can solve for y from there.
The eqn of a straight line is: y=mx+c: m is the slope & c the y-intercept. All you have to do is rearrange the equation, to get the respective slope 7 intercept
2007-02-22 14:10:37 · answer #2 · answered by raqandre 3 · 0⤊ 0⤋
I'll tell you the 1st answer:
1st: y=mx+b
therefore, 17 = (-9)7+b ===>b=80, right?
now, y= (-9)8+80 = 8!!!!!
2007-02-22 14:20:35 · answer #3 · answered by DuckyWucky 3 · 0⤊ 0⤋
your y intercept is -6 i believe....anytime you have something like that just plug 0 in for the way and whatever the x is is your y intercept....just like you x intercept for that one would be...-3,,,i think....
2007-02-22 18:14:42 · answer #4 · answered by Travis S 2 · 0⤊ 0⤋