Chapter 5 Straight Line Graphs

Question 1

what is the formula for the gradient m of a line joining the point with coordinates (x1, y1) to the point with coordinates (x2, y2)?

Answer 1

m = (y2 - y1)/(x2 - x1)

Question 2

what are the two ways the equation for a straight line can be written?

Answer 2

1. y = mx + c where m is the gradient and c is the y-intercept
2. ax + by + c = 0 where a, b and c are intergers

Question 3

what is the formula for the equation of a line with gradient m that passes through the coordinate (x1, y1)?

Answer 3

y - y1 = m(x - x1)

Question 4

what is the relationship between parallel lines gradients?

Answer 4

they are the same

Question 5

what is the relationship between perpendicular lines gradients?

Answer 5

if a line has a gradient of m, a line perpendicular to it has a gradient of -1/m

Question 6

how can you find the distance between (x1, y1) and (x2, y2)?

Answer 6

d^2 = (x2 - x1)^2 + (y2 - y1)^2

Question 7

what does direct proportion mean?

Answer 7

two quantities are in direct proportion when they increase at the same rate