Question

Devon wants to write an equation for a line that passes through 2 of the data points he has collected. The points are (8, 5) and (–12, –9). He writes the equation

7x – 10y = 3. Is this a good model? Explain your reasoning.

Answer 1

Using the y=mx+b format,
m the slope = (5--9)/(8--12) = 14/20 = 7/10=0.7

y-y1 = m(x-x1)
y-5 = .7(x-8) = .7x-5.6
y = .7x +0.6
10y = 7x + 6
so 7x - 1y = -6 any your equation is almost correct.

Answer 2

(8,5)(-12,-9)
slope = (-9-5) / (-12 - 8) = -14/-20 = 7/10

y = mx + b
slope(m) = 7/10
(8,5)..x = 8 and y = 5
now we sub and find b, the y int
5 = 7/10(8) + b
5 = 56/10 + b
5 - 56/10 = b
50/10 - 56/10 = b
-3/5 = b

equation is : y = 7/10x - 3/5...but we need it in standard form

y = 7/10x - 3/5
-7/10x + y = -3/5
7x - 10y = 6

no, 7x - 10y = 3 is not a good model....because neither of ur points, when subbed in, will make this equation true