Year 9 Linear Equations In 2 Variables

Question 1

Inverse of x

Answer 1

/

Question 2

Inverse of +

Answer 2

-

Question 3

Inverse of square

Answer 3

Square root

Question 4

Inverse of cube

Answer 4

Cube root

Question 5

Cross multiplication

Answer 5

A C
— x —
B D
AD = BC

Question 6

What could gradient represent in cost per hour

Answer 6

Hourly rate

Question 7

What could y - intercept represent in cost per hour

Answer 7

Call out charge

Question 8

Solving 2 equations simultaneously
Graph method

Answer 8

Rearrange one equation with x as the subject
Rearrange other equation with y as the subject
Plot both lines on a graph
The coordinate where the 2 lines cross is x and y respectively

Question 9

Solving 2 equations simultaneously
Substituting method

Answer 9

Rearrange one of the equations to make either x or y the subject
In the other equation, replace x or y, which ever you chose to make the subject previously, with the rearranged equation
Solve for both x and y

Question 10

Solving 2 equations simultaneously
Elimination method

Answer 10

Label your equations with numbers
Decide which variable you will eliminate (for example variable x)
Make the coefficient of x the same magnitude in each equation (by multiplying each equation by the appropriate number)
Now add the new equations (if coefficients are different signs) or subtract (if coefficients are the same size.)
Solve for y (because x is eliminated)
Substitute your value of y back in either equation you started with to find x.

Question 11

2 lines are parallel if

Answer 11

They have the same gradient