Quantitative Reasoning questions?

AT FIRST:

standard equation of a line is:

f(x)= ax + b

a is the gradient, so if u have a= 4 then at an x of 1 you will get a y=4*1= 4 (the higher this number is the steeper the slope)

b is the displacement. It gives you the number where the line will cross your Y-axis.

Why? Because when x=0 it will give you y=a*0 +b=b

FIRST QUESTION:

So we have y= ax + b

at first you are going to calculate a.

Gradient = (change Y) / (change X)

So in this question: a = (-2 - -8) / (2 - -3) = 6/5

We now have y=(6/5)x + b

What we know more is that this line goes through the point (2, -2) so if you fill this in you will get:

-2 = (6/5)*2 + b => -2 = 12/5 +b => b = -4 2/5

ANSWER 1:

f(x) = (5/6)x - 4 2/5

SECOND QUESTION

the slope is 7 so a=7.

gives you: y=7x + b

Again we know that it goes through some point (given) and that is (-7, -3)

Fill in again gives you:

-3 = 7 * -7 +b

b = 52

ANSWER 2:

y=7x + 52