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

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

y = mx + b
slope(m) = 7/10
use either of ur points.....(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

so ur equation is : y = 7/10x - 3/5.....now we put it in standard form

y = 7/10x - 3/5...multiply by 10
10y = 7x - 6.....subtract 7x
-7x + 10y = -6....multiply by -1
7x - 10y = 6

So.....7x - 10y = 3.... IS NOT a good model. Because ur points are not a solution to ur equation.