check math
posted by Anonymous .
3) FInd an equation of the line containting the given pair of points.
(3,4) and (9,6)
MY ANSWEAR: 2/5X+9
4)Find an equation of the line having the given slope and containing the given point.
m=2/3 (7,7)
MY ANSWEAR: 2/3X14/3X

Okay, first we need to get the slope of the line connecting the two given points by using:
Slope (m) = (y2  y1)/(x2  x1)
Therefore: m = (6  4)/(9  3)
m = 2/6 = 1/3
So the slope of the line joining (3,4) and (9,6) is 1/3.
To find the equation of the line use the equation:
y  y1 = m(x  x1)
You can use either point for the (x1,y1)
I'll use (3,4)
So we get:
y  4 = (1/3)*(x  3)
3*(y  4) = (x  3)
3y  12 = x  3
3y = x  3 + 12
3y = x + 9
y = (1/3)*x + 3
So y = (1/3)x + 3 is your equation for the line for part 3).
For part 4) you can go straight to the
y  y1 = m(x  x1) equation.
So subbing in we get:
y  (7) = (2/3)*(x  7)
y + 7 = (2/3)*(x  7)
3*(y + 7) = 2*(x  7)
3y + 21 = 2x  14
3y = 2x  14  21
3y = 2x  35
So
y = (2/3)x  (35/3)
Ok, I hope that helps!