Drawing & Using Graphs: WJEC GCSE Intermediate November 2019 Unit 2 Q12

Intermediate November 2019 Unit 2 Q12

WJECIntermediateCurrent spec6 marksDrawing & Using Graphs Substitution

12. The table below shows some of the values of \(y = x^2 - 2x - 4\) for values of \(x\) from –3 to 4.

\(x\)	−3	−2	−1	0	1	2	3	4
\(y = x^2 - 2x - 4\)	11	4	−1	−4		−4	–1	4

(a) Complete the table by finding the value of \(y\) when \(x\) = 1. [1]

(b) On the graph paper below, draw the graph of \(y = x^2 - 2x - 4\) for values of \(x\) from –3 to 4. [2]

(c)

(i) Draw the line \(y + x = 4\) on the graph paper. [2]

(ii) Write down the values of \(x\) where the line \(y + x = 4\) cuts the curve \(y = x^2 - 2x - 4\). [1]

Values of \(x\) are ……………… and ………………

Mark scheme (a)

Scheme	Marks	Comments
–5	B1

Mark scheme (b)

Scheme	Marks	Comments
At least 7 correct plots and no incorrect plot.	P1	F.T. ‘their (1,−5)’ Allow ± ‘½ a small square’.
A smooth curve drawn through their plots.	C1	F.T. ‘their 8 plots’. OR a curve through the 7 given points and (1,−5) Allow intention to pass through their plots. (± 1 small square horizontal or vertical.)

Mark scheme (c)

Scheme	Marks	Comments
(i) Line y + x = 4 drawn.	B2	B1 for a straight line going through(0,4) or (4,0) BUT NOT line y = 4 nor line x = 4
(ii) −2·4 AND 3·4	B1	F.T. intersection of ‘their curve’ with ‘their y + x = 4 ’ (even for line y = 4) only if exactly two points of intersection. Must be seen to intersect their curve at two points. Allow ± ‘1 small square’.