Simultaneous Equations: WJEC GCSE Intermediate November 2022 Unit 2 Q19

Intermediate November 2022 Unit 2 Q19

WJECIntermediateCurrent spec4 marksSimultaneous Equations

19. Solve the following simultaneous equations using an algebraic (not graphical) method.
Do not use a trial and improvement method.
You must show all your working. [4]

\[\begin{aligned}3x+5y&=-2\\5x+4y&=-12\end{aligned}\]

Mark scheme

Scheme	Marks	Comments
Method to eliminate one variable e.g. equal coefficients AND appropriate intention to add or subtract or use a method of substitution.	M1	Allow one error in one term (not the term with equal coefficients).
First variable found \(x = -4\) or \(y = 2\)	A1	CAO. Answer must be whole number (e.g. not \(x\) = –12/3)
Substitute to find the 2^nd variable.	m1	FT substitution of their ‘1^st variable’ if M1 gained.
Second variable found.	A1	If FT leads to a whole number answer, it must be shown as a whole number. Otherwise, accept a fraction. No marks for ‘trial and improvement’. No marks for an unsupported answer.