Straight Lines Objectives: C Grade Find the gradients and y-intercepts of equations in the form 4y + 3x = 8 by rearranging the equation Prior knowledge: Recognise the equations of straight line graphs and find the gradients of straight line graphs Rearrange equations to make a variable the subject

Straight Lines Name the equation: 1 y = x - 4 2 y = -x + 9 3 1 2 3 4 5 6 7 8 9 10 -9 -8 -7 -6 -5 -4 -3 -2 -1 -10 x y 1 y = x - 4 2 y = -x + 9 3 y = -2x + 4 4 y = -½x 5 y = ½x + 3 6 y = 2x - 3

Straight Lines Example 1 Rearrange this equation into the form y = mx + c y + x = 8 Use the inverse function to move x to the other side of the equation Example 2 -x y = 8 - x Rearrange this equation into the form y = mx + c 2y + 4x = 8 Use the inverse function to move x to the other side of the equation -4x 2y = 8 - 4x Use the inverse function to get y = ÷2 y = 8 - 4x 2 Simplifies to: y = 4 – 2x

Straight Lines Find the gradient of this straight line and where it crosses the y-axis y + 3x = 6 Rearrange this equation into the form y = mx + c y = -3x +6 -3 6 The gradient is: The y intercept is:

Find the gradients and intercepts of these equations: Straight Lines Find the gradients and intercepts of these equations: 1. 2y - x = 4 Gradient _____ y intercept _____ 2. y + 2x = 3 3. 4y + 3x = - 8 4. y - 4x = -6 5. 3y - 4x = 8 6. - 3x + 2y = 6 ½ 2 -2 3 -¾ -2 4 -6 1 3 2 3 1 2 3

Straight Lines Worksheet 1 Name the equation: 1 2 3 4 5 6 y x 1 2 3 4 1 2 3 4 5 6 7 8 9 10 -9 -8 -7 -6 -5 -4 -3 -2 -1 -10 x y 1 2 3 4 5 6

Straight Lines Worksheet 2 Find the gradients and intercepts of these equations: 1. 2y - x = 4 Gradient _____ y intercept _____ 2. y + 2x = 3 3. 4y + 3x = - 8 4. y - 4x = -6 5. 3y - 4x = 8 6. - 3x + 2y = 6