Thread: Simultaneous Equations, Non Linear Equations and Equations with 3 unknown pronumerals

I have these exercises for homework but I dont understand them, I have read the examples but I can't comprehend how the examples work.

If you know how to do these could you please explain them in simple terms. I am stressing out over this please help

Originally Posted by Needhelpatmaths

I have these exercises for homework but I dont understand them, I have read the examples but I can't comprehend how the examples work.

If you know how to do these could you please explain them in simple terms. I am stressing out over this please help

If you expect to get help you will need to post the actual questions.

Ok I will provide a sample questionof each:

Simultaneous Equations:

3a + 2b = 5 and 2a - b = -6


Non Linear Equations:

xy = 6 and x + y = 5


Equations with 3 Unknown Variables:

a - b + c = 7 , a + 2b - c = -4 and 3a - b - c = 3

Originally Posted by Needhelpatmaths

Ok I will provide a sample questionof each:

Simultaneous Equations:

3a + 2b = 5 and 2a - b = -6

Mr F says:

3a + 2b = 5 .... (1)
2a - b = -6 .... (2)

Multiply equation (2) by 2 and add it to equation (1): 7a = -7 => a = -1.

Substitute a = -1 into either equation and solve for b.


Non Linear Equations:

xy = 6 and x + y = 5

Mr F says:

xy = 6 .... (1)
x + y = 5 => y = 5 - x .... (2)

Substitute equation (2) into equation (1):

x(5 - x) = 6 => 5x - x^2 = 6 => x^2 - 5x + 6 = 0.
Therefore x = 2, 3.

Substitute the values of x into equation (2) and solve for y.


Equations with 3 Unknown Variables:

a - b + c = 7 , a + 2b - c = -4 and 3a - b - c = 3

Mr F says:

a - b + c = 7 => c = 7 - a + b.... (1)
a + 2b - c = -4 .... (2)
3a - b - c = 3 .... (3)

Substitute equation (1) into equations (2) and (3) and simplify:

2a + b = 3 .... (A)
2a - b = 5 .... (B)

Add equations (A) and (B) together: 4a = 8 therefore a = 2.

Substitute a = 2 into equation (A) or (B) and solve for b. Then substitute the values of a and b into equation (1) and solve for c.

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