-13.5914091423 is what I got from a calculator.
Answer:
y = 4/3x + 1.
Step-by-step explanation:
The equation of the lines passing through (2,1) and (6,7) is:
y - 7 = (7-1)/(6- -2)(x - 6)
y - 7 = 6/8(x - 6)
y = 3/4(x - 6) + 7
y = 3/4x + 5/2.
So the line perpendicular to it has slope -1/3/4 = -4/3:
y - 9 = -4/3(x + 6)
y = -4/3 x - 8 + 9
y = 4/3x + 1.
(x + 8)(x - 6)
to factorise consider the factors of - 48 which sum to + 2
These are + 8 and - 6 thus
x² + 2x - 48 = (x + 8)(x - 6)