CAIE IGCSE Mathematics Core C2.5 Equations

Covered syllabus points

C2.5.1 Construct expressions, equations and formulas C2.5.2 Solve linear equations C2.5.3 Solve simultaneous linear equations C2.5.4 Change the subject of simple formulas

[Maximum number: 7]

(a)

P=8x+3y
Find the value of x when P=21 and y=-5.
x=

[ 2 ]

4.5
M1 for $21=8x+3\times(-5)$ oe or better

(b)

Nasser has x marbles.

Selina has 15 more marbles than Nasser.
Hanif has 3 times as many marbles as Selina.
In total they have 150 marbles.
Find the value of x.

[ 5 ]

18
B1 for x+15 or $3\times\text{their }(x+15)$ oe
M1 for $x+\text{their }(x+15)+\text{their }3(x+15)=150$ or better
M1 for 5x+60=150 or better, or their linear equation simplified to ax+b=150
M1 for solving their ax+b=c to $x=\frac{150-b}{a}$

[Maximum number: 2]

Solve.

6 x-5=2 x+13

$4\frac12$ , 4.5 or $\frac92$

M1 for 6x-2x=13+5 or better.

[Maximum number: 3]

Solve the simultaneous equations.
$\begin{aligned}3x-5y&=22\\7x+10y&=8\end{aligned}$ $\begin{aligned}x&=\\y&=\end{aligned}$

$\begin{aligned}x&=4\\y&=-2\end{aligned}$

M1 for correct method to eliminate one variable.
A1 for one correct answer.
If M0 scored, SC1 for 2 values satisfying one of the original equations.

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CAIE IGCSE Mathematics Core C2.5 Equations Topic Practice

Covered syllabus points

Question 1

Question (a)

Question (b)

Question 2

Question 3