CAIE A-Level Mathematics 1.3.1 Straight lines

Practise forming straight-line equations from two points or from a point and gradient, using equivalent equation forms confidently.

Exam points

calculate a gradient from two points, then form the line equation through either point

[Maximum number: 2]

Figure for Question 1.3.1—Straight lines question 1 — CAIE A-Level Mathematics AS

The diagram shows the curve with equation $x=y^{2}+1$ . The points A(5,2) and B(2,-1) lie on the curve.

Find an equation of the line A B.

Gradient of $A B=\frac{2-(-1)}{5-2}$

M1

Expect 1, must be from $\Delta y / \Delta x$ .

Equation of A B is y-2=1(x-5) or y+1=1(x-2)

A1

OE. Expect y=x-3.

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1.3.1—Straight lines question 1