Question

find the slope of the line that passes through (-2,1), (1,10).
A: 3
B: -3
C: 1/3
D: -1/3

Which equation represents a direct variation? What is the constant of variation?
A: 3y=2x+1;1
B: y=-5x-11;5
C: 4y=-12x;-3
D: y+7=2x-1;7

Suppose y varies directly with x, and y=12 when x=-3. what is the value of y when x=6?

A: -24
B: 2
C: -2
D: -4

Answer 1

the slope is (1-10)/(-2-1) = ?

direct variation is y = kx
so, which choice looks like that?

y = kx, so y/x = k, a constant value. So, you want y such that
y/6 = 12/-3

Answer 2

What is the equation of the line that passes through the points (0,4) and (3,-2)?


What is the equation of the line through (5,1) with a slope of -3?

Answer 3

review two-point and point-slope forms.
The 2-point is just like point-slope, but you have the extra step of finding the slope first.

The slope of the line through (0,4) and (3,-2) is (-2-4)/(3-0) = -2
So, now you have a point and a slope. The line is thus
y-4 = -2(x-0)
or
y+2 = -2(x-3)
Those both describe the same line.

Now use the point-slope form on the other line