Can you explain how to find straight line equations?

Straight line equations always come in the form y=mx+c, where m is the gradient of the line (how steep it it) and c is the point where the line crosses the y axis (the y intercept).If you are given two points say 1 - (2, -4) and 2 - (6, 8) we can find the equation of the line that runs through them.First we find the gradient - this is the change in y over the change in x, (y2 - y1) / (x2 - x1)Here this is (8- (-4)) / (6 -2) = 12/4 = 3Next we plug this into the form of the equation and use one of the points to find ceg using point 1, -4 = 3 x 2 + cwe then re arrange -4 - 6 = cTherefore c = -10Finally we use all the values we have found to create the straight line equation,y=3 x -10

JQ

Related Maths GCSE answers

All answers ▸

Solve 3x - 5 < 16


White paint costs £2.80 per litre. Blue paint costs £3.50 per litre. White paint and blue paint are mixed in the ratio 3 : 2. Work out the cost of 18 litres of the mixture.


A rectangle has a shorter side with a length of x and a longer side with a length of x + 8, the perimeter of the rectangle is 80cm. Calculate the value of x.


differentiate x^2+10x+13