Dr. J's Maths.com
Where the techniques of Maths
are explained in simple terms.

Algebra - Equations - 3 Simultaneous equations.
Test Yourself 1
.


 

Solve the following sets of 3 equations for the relevant 3 variables:
These are challenging but you could use them in parts of at least an advanced Mathematics course.

1:

x + 2y - z = -5

2x - 3y + 4z = 28

4x + 5y - 3z = -10

Hint.We could remove z by multiplying Eqn 1 by 4 to equate with Eqn 2 - then add.
Then multiply Eqn 1 by 3 to equate to Eqn 3 - then subtract.
The result is two equations in x and y - so proceed as usual.

2:

e - f + g = 10

4e + 2f - 3g = 8

3e - 5f + 2g = 34

Hint.I suggest you work to eliminate g by forming two equations -
in e and f.
To form these two new equations, multiply Eqn 1 by 3 and then Eqn 1 by 2.
3.

6x + 4y - 2z = 0

3x - 2y + 4z = 3

5x - 2y + 6z = 3

4:

2a - b - c = 9

5a + 2c = -3

7a - 2b = 1

5.

3p - q - 2r = -15

20p - 3q - 5r = -15

5p + 2q + 3r = -16

6.

x - 2y = 3

4y - 3z = 4

x + 3z = 2

 

1. The general form of a parabola could be written as

y = k(x - a)2 + b

Given that the parabola passes through the points (-3, 7), (0, -5) and (2, -3), find the values of a, b and k and write down the equation of the parabola.