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9.04 Simultaneous equations

Worksheet
Check simultaneous solutions
1

Explain how to determine that a given ordered pair is a solution of a system of equations.

2

Determine whether \left(5, 2\right) is a solution of the given system of equations:

x + y = 7 \\ x - y = 3
3

Determine whether \left(4, 17\right) is a solution of the given system of equations:

\begin{aligned} y &= 6 x - 7 \\ 4 x + 3 y &= 67 \end{aligned}
4

Determine whether the following points are solutions of the given system of equations:

a

\left(2, 5\right)

b

\left(3, 4\right)

\begin{aligned} x + y &= 7 \\ 4x + 5y &= 32 \end{aligned}
5

Determine whether the following points are solutions of the given system of equations:

a

\left(5, 3\right)

b

\left(7, 13\right)

\begin{aligned} 4 y &= 5 x - 13 \\ 5 x - y &= 22 \end{aligned}
6

Determine whether the following points are solutions of the given system of equations:

a

\left(5, -1\right)

b

\left(4, 3\right)

\begin{aligned} 4 x &= 19 - y \\ x - 3 y &= - 5 \end{aligned}
7

Determine whether the following points are solutions of the given system of equations:

a

\left(4, 16\right)

b

\left(2, 18\right)

\begin{aligned} y &= 5x - 4 \\ y &= -x + 20 \end{aligned}
The graphical method
8

Describe the graphical solution of a system of two linear equations.

9

Consider a system consisting of two straight lines with different gradients. How many points of intersection will the lines have?

10

The following graph displays a system of two equations:

State the solution to the system in the form \left(x, y\right).

-4
-3
-2
-1
1
2
3
4
5
6
7
x
-7
-6
-5
-4
-3
-2
-1
1
2
3
4
y
11

For each of the following pairs of linear equations:

i

Sketch the lines of the two equations on the same number plane.

ii

Hence, state the values of x and y which satisfy both equations.

a

y = x + 0 and y = - 1

b

y = \dfrac {x}{3} + \dfrac {1}{3} and - 8 y = 8 x + 8

c

y = 2 x + 2 and y = - 2 x + 2

12

How many solutions does the given system of equations have? Explain your answer.

\begin{aligned} x + y &= 5 \\ 4 x + 4 y &= 20 \end{aligned}
13

Consider the following system of equations:

a

For which value of b does the system have an infinite number of solutions?

b

For which values of b does the system have no solutions?

\begin{aligned} x + y &= 3 \\ 2x + 2y &= b \end{aligned}
The substitution and elimination methods
14

Solve the following pairs of simultaneous equations using the substitution method:

a

y=-5x - 23 \\ y = 7x + 25

b

y=5x+34 \\ y=3x+18

c
\begin{aligned} y & = 5x + 12 \\ 4y & = 28x + 72 \end{aligned}
d

\begin{aligned} y &= -4x - 17 \\ 3y &= 21x + 147 \end{aligned}

e

\begin{aligned} y &= -6 x - 26 \\ x + y &= -6 \end{aligned}

f

\begin{aligned} y &= 3 x - 18 \\ x - y &= 10 \end{aligned}

g

\begin{aligned} y &= -5 x + 22 \\ 6 x + y &= 26\end{aligned}

h

\begin{aligned} y &= 6 x - 2 \\ -3 x - y &= -7 \end{aligned}

i

\begin{aligned} y &= 8 x - 30 \\ 5 x + 9 y &= 38 \end{aligned}

j

\begin{aligned} y &= -2 x - 1 \\ x + 2 y &= 13 \end{aligned}

k

\begin{aligned} 4 x + 3 y &= 52 \\ 7 x - 5 y &= 9 \end{aligned}

l

\begin{aligned} x &= -5y - 27 \\ x &= 7y + 45 \end{aligned}

m

\begin{aligned} x &= -4 y - 39 \\ 4 x &= 24 y + 164 \end{aligned}

n

\begin{aligned} x &= 4 y - 27 \\ 2 y + x &= 21 \end{aligned}

o

\begin{aligned} x &= 3 y - 21 \\ 8 y + 5 x &= 79 \end{aligned}

p

\begin{aligned} 3 y + 2 x &= 37 \\ 9 y - 5 x &= 56 \end{aligned}

15

Consider the following system of linear equations:

\begin{aligned} y &= x + 8 \\ y &= - 7 x + 16 \end{aligned}
a

Use the substitution method to solve the system of equations.

b

Use the elimination method to solve the system of equations.

c

Do both methods give the same solution?

16

Consider the given system of equations:

Equation 1: 3x - 7y = 4

Equation 2: -12x + 28y = -16

a

Rearrange Equation 1 to find x in terms of y.

b

Substitute your expression for x into Equation 2 and solve for the value of y.

c

State whether the system of equations is inconsistent, dependent or independent.

17

Solve the following pairs of simultaneous equations using the elimination method:

a
\begin{aligned} 2x + 5y &= 44 \\ 6 x - 5 y &= -28 \end{aligned}
b
\begin{aligned} 8 x + 3 y &= -11\\ -8 x - 5 y &= 29 \end{aligned}
c
\begin{aligned} - 5 x + 16 y &= 82\\ 25 x - 4 y &= 122 \end{aligned}
d
\begin{aligned} 2 x - 5 y &= 1 \\ -3 x - 5 y &= -39 \end{aligned}
e
\begin{aligned} 7 x - 4 y &= 15 \\ 7 x + 5 y &= 60 \end{aligned}
f
\begin{aligned} - 6 x - 2 y &= 46 \\ - 30 x - 6 y &= 246 \end{aligned}
g
\begin{aligned} - \dfrac {x}{4} + \dfrac {y}{5} &= 8 \\ \dfrac {x}{5} + \dfrac {y}{3} &= 1 \end{aligned}
h
\begin{aligned} y + \dfrac {x}{2} &= 3 \\ \dfrac {x}{5} + 3 y &= - 4 \end{aligned}
18

Solve the following pairs of simultaneous equations using an appropriate algebraic method:

a

\begin{aligned} x + y &= 8 \\ 2x - 3y &= 26 \end{aligned}

b

\begin{aligned} y &= 2x + 16 \\ y &= 3x + 21 \end{aligned}

c

\begin{aligned} y &= 4x - 17 \\ x + y &= 38 \end{aligned}

d

\begin{aligned} 3x + y &= 22 \\ y &= -2x + 10 \end{aligned}

e

\begin{aligned} 2x + y &= 5 \\ 5x + 3y &= 9 \end{aligned}

f

\begin{aligned} 11x + 6y &= 27 \\ 7x + 6y &= -9 \end{aligned}

g

\begin{aligned} 6x + 10y &= 59 \\ -4x + 5y &= 19 \end{aligned}

h

\begin{aligned} 18x - 7y &= -64 \\ 3x + 5y &= 14 \end{aligned}

i

\begin{aligned} 5x - 3y &= 46 \\ 3x + 10y &= 4 \end{aligned}

j

\begin{aligned} \dfrac{x}{2} + 3y &= -6 \\ - \dfrac{x}{4} + y &= -7 \end{aligned}

Use technology
19

Solve the following pairs of equations by using your CAS calculator, or other technology, to graph the lines on the same number plane:

a
\begin{aligned} y &= 5 x - 7 \\ y &= - x + 5 \end{aligned}
b
\begin{aligned} x &= 8 \\ y &= 4 x + 8 \end{aligned}
c
\begin{aligned} y &= 3 \\ y &= 2 x - 3 \end{aligned}
20

Graph the following lines on the same set of axes on your CAS calculator, or other technology, to determine how many solutions there are to the system of equations:

\begin{aligned} 6x - y &= 1 \\ 12x - 2y &= 2 \end{aligned}
21

Consider the following equations:

  • Equation 1: x - y = - 6

  • Equation 2: - x + 2 y = 9

  • Equation 3: 2 x - 7 y = - 42

Graph the following pairs of equations using technology, and state the solution to each system of equations:

a

Equations 1 and 2

b

Equations 1 and 3

c

Equations 2 and 3

22

Solve each of the following systems of linear equations using the solving functionality of your CAS calculator:

a

y = 4 x + 35 \\ y = 2 x + 21

b

y = 2.7 x - 17.41 \\ y = - 9.8 x + 13.84

c

\dfrac {1}{3} x + \dfrac {2}{3} y = 1

\dfrac {1}{2} x + \dfrac {1}{3} y = 7

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Outcomes

1.3.3.1

solve a pair of simultaneous linear equations in the format 𝑦 =𝑚x + 𝑐, using technology when appropriate; they must solve equations algebraically, graphically and by substitution, not using the elimination method

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