Fine the equation of a line.?

Question

I need help on how to solve these and show my work

Find the equation of the line that passes through (-7,-9) and (-8,0)

Answer 1

the slope will be (0 + 9) / (-8 +7) = 9/-1 = -9 --> m = -9

now take a point and plug it in to the formula y = mx + b.
0 = -9(-8) + b ---> b = -72

now your done. y = -9x - 72

Answer 2

The equation is: y = mx + b

m = the slope (or rise over run) = in this case 9/-1 = -9

y = -9x + b

to find b plug in one set of coordinates, x = -8, y = 0
0 = -9(-8) + b
0 = 72 + b
-72 = b

check it with the other set of coordinates
-9 = -9(-7) + b
-9 = 63 + b
-9 - 63 = b
-72 = b

so the equation of this line is:
y = -9x -72

Answer 3

the equation of a line is y=mx+b where m is the slope and b is the y intercept. first start by calculating m. m is the slope is = rise/run. this can be expressed by (y2-y1)/(x2-x1) since you have two points, plug these coordinates in ===> (0-(-9))/(-8-(-7)) this yields 9/-1 which gives a slope of -9. in order to calculate b, the y-intercept, plug the slope and one of the points into the equation and solve. -9=(-9)(-7)+b this gives -9=63+b. simplifying yields b=-72. now plug this back into the equation. you answer is y=-9x-72. check by plugging in the other coordinate pair into the equation. 0=(-9)(-8)-72 ==> 0=72-72.

Answer 4

first use the formula to find the slope (X1,Y1) (X2Y2)
m= y2-y1/x2-x1
= 0-(-9)/ (-8-(-7)
= 9/-1
=-9
Plug the slope into y=mx+b and using any one of the given coordinate on (-7,-9) Solve
so far you have
y=-9x+b
-9=-9(-7) + b
solve for b and you get 83
Thefore the final answer is y=-9x-72

Answer 5

Slope m=(0--9)/(-8--7)=9/(-1)=-9
y=-9x+b
0=-9*-8+b
0=72+b
b=-72
y=-9x-72

Answer 6

0-(-9)/-8-(-7)=9/-1= -9
y=mx+b
0= -9(-8)+b
0= 72+b
b= -72

y= -9x-72