Mathaholic

This is a simple subsitution.

3x+4y=5

2x+5y=15

To do this it is easier to use the elimination method

I multiplied the formulas buy 2 and 3 respectively to make x the common one but it can be done the other way round with y.

Anyway...

(multiply by 2)

6x+8y=10

(multiply by 3)

6x+15y=45

cancel out the x's

You get: 7y=35

Therefore y=5

Now substitute the above into the original equation...

3x+20=5

3x=-15

x=-5

Proof: -10+25=15

ohhhh yes.

I completely forgot to times 1 by the two equations...

Im an idiot.

Anyway good working Cpill, hope you appreciate the 5 stars :)

Please do not swear here, this forum was made for maths not swearing.

Thank you :)

By the way im back!!!

Sorry for the absence, hopefully it wont happen again until June (When i have my very important maths exam)

What you do is that you time the denominator with the number diagonally opposite.

You will get (2x+3)(2x+1)-(x-4)(2x-8)=1

It is now an wasy quadratic equation which can now be solved easily :)

The area of a circle is:

pi * radius^2

To get the radius you halve the diameter to get 10.5

You square it and times it by pi to get:

346.3605901

 You use the indices rule where you add the powers when you multiply so you get x^4+x^2=x^6

If you only have three angles then you know the shape the triangle will take but you will not know the exact length of a side.

You could have a triangle with all those angles and sides of 34, 23,78 and you could also have another triangle with the same angles and sides of 68,46,156.

(78+x)-2574=420

Since there is no number next to the brackets we assume it is one and multiply it out as such.

Therefore we get:

78+x-2574=420

Now to simplify:

x-2096=420

x+420+2096

x=2516

:) :) :)