数学 Relations and Functions

1)
to find intersection point, set f(x) = g(x).
(5/2)x + 1 = 3
(5/2)x = 2
x = 2 * (2/5)
x = 4/5
x = 0.8
answer: A
2)
given point B(-4,9) and C(-7,10),
slope m = (9-10)/(-4-(-7))
= -1/3
because we need an equation that is perpendicular to this line, we know that it's the negative reciprocal, so the new slope m = 3
y - y1 = m(x-x1)
y-0 = 3(x-6)
y = 3x - 18
answer: A
3) around 6th grade.