Algebra? maybe?

Question

oh jeez, so i'm reviewing for the SATs and i've pretty much forgotten most of the math stuff that i learned like 243 years ago. anyways i think this question is algebra stuff? idk but heres the question:

what is the y-intercept of the line that goes thru the points (6,14) and (18,8)?

i vaguely remember the whole x=0 stuff but for the most part it's gone... any help please? thanks in advance!!

Answer 1

you use the slope formula to find the slope of the line,

m = y2-y1 / x2-x1 = 8-14 / 18-6 = -6/12 = -1/2.

Then you plug it into the formula y = mx + b

y = -1/2x + b. If you plug any point,

(6,14) --> 14 = -1/2(6) + b --> b = 17

so y-intercept is 17.