All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.

(i)
At (1.6, -2.4), ~0.390625a + 1.6b + c = -2.4 \rightarrow (1)

At (-0.7, 3.6), ~\frac{1}{0.7^2}a - 0.7b + c = 3.6 \rightarrow (2)

\frac{dy}{dx}|_{x=1} = 2

\Rightarrow -2a + b = 2 \rightarrow (3)

Using GC, a \approx -3.593, b \approx -5.187, c \approx 7.303 (to 3 decimal place)

(ii)
Using GC, x = -0.5890038 \approx -0.589 (to 3 decimal place)

(iii)
y = -5.19x +7.30 (to 3 sig fig)

Back to 2015 A-level H2 Mathematics (9740) Paper 1 Suggested Solutions

KS Comments:

Students should be careful when they substitute. Very easy to make a careless mistake here. No need to actually rearrange the question actually. And since the question wants answers in 3 dp for (i) and (ii), but didn’t state anything for (iii) we should round off to 3 significant figures as per normal.

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