Edexcel IALMathematicsGeneral Applications5 Marks

Figure 1 shows a sketch of the curve C with equation y = 2^x. The curve C crosses the y-axis at the point A. The point B has x-coordinate 4 and lies on C. [Figure 1 shows an exponential curve y=2^x, passing through (0,1) and a point B at x=4.] (a) Write down the coordinates of A. (b) Find the equation of the straight line L which passes through A and B. Give your answer in the form y = mx + c.

(a)Write down the coordinates of A.[1]
(b)Find the equation of the straight line L which passes through A and B. Give your answer in the form y = mx + c.[4]

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Mark scheme

Marking points from the official mark scheme. The mark or mark type is shown in brackets.

B1 for A = (0, 1).
M1 for finding the y-coordinate of B: y = 2^4 = 16.
A1 for B = (4, 16). (Can be implied by correct gradient calculation).
M1 for calculating the gradient of AB: m = (16 - 1) / (4 - 0).
A1 for y = (15/4)x + 1 (or y = 3.75x + 1).

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