Question

What is the equation in point-slope form of a line that passes through the points (−4, −1) and (5, 7) ?

y+1=87(x+4)

y−1=89(x−4)

y+4=98(x+1)

y+1=89(x+4)

Answer 1

C. we try y + 4 = 98 + 1 = 98/98 + 4 = 102/ 98 = 1.04 so inverse is 8 / 9

Explanation:

y2-y1 / x2-x1

7--1 / 5--4

7+1 / 5+4

8 / 9

m = 8/9

y+1 = ? (x+ 4)

we know y^1 will be added or subtracted at end to show the +1 so added.

so we try 87x + 348 + 1 = 87x + 349 = 87/349 = 1/4 so no

we try 89x + 349 = 89/349 = 0.255 so no

we try y + 4 = 98 + 1 = 98/98 + 4 = 102/ 98 = 1.04 so inverse is 8 / 9

we try y+1 = 89x + 356 + 4 = 360/89 = 1/4 = 0.247222222 so no

we test

89/.360 = 1/4 so no

we test 102/ 98 = 0.960784314 = 1 - 0.4

therefore 1 / 1.4 = 0.714285714 which is 7/10 - 10-1.4 = 8.6

and as 7/10 is actually higher 7.14 and 8.6 when we add each side 0.4 we get 8/9

Answer 2

The answer is y+1=8/9(x+4)