PLEASE HELP! I am going crazy.

If x+y=1, x^2+y^2=4, x^3+y^3=?

^x=exponent

Lol, first day of Advanced Algebra and Trig and I feel like I'm lost -___-

Please explain slowly.

Lol, makes no sense to me. If you take the square roots of the second one, it would mean that x+y=2...

This isn't simple Algebra that's why it doesn't sense to you (or me).

well if it follows a set pattern then the answer may be 6, it could also be 9. seeing as i failed trig it may not be that useful to listen to me tho

Is that actually trig? I think that's just algebra... I don't see anything related to trig in it (I myself am taking trig now)

Fang wrote:Is that actually trig? I think that's just algebra... I don't see anything related to trig in it (I myself am taking trig now)

trig and algebra go hand in hand

Well it's "Advanced Algebra and Trig", this is also known as "Pre-Calculus"

Not trig then.

I'll post it on Sal's and see if they can help.

Here it is:

How come you changed the result of the first equation into 2 rather than 1 ?

I'd substitute for x or y from the first equation:

x+y=1 --> y=1-x

Then substitute y into the second equation and solve for x as a quadratic. Does that help? I get two possible values for each of x and y, but I'll leave you to work them out for yourself...

Fang wrote:Here it is:

How come you changed the result of the first equation into 2 rather than 1 ?

I'd substitute for x or y from the first equation:

x+y=1 --> y=1-x

Then substitute y into the second equation and solve for x as a quadratic. Does that help? I get two possible values for each of x and y, but I'll leave you to work them out for yourself...

No sorry. Thanks though

I finally understood it today

If x+y=1, x^2+y^2=4, x^3+y^3=?

x^3+y^3=(x+y)(x^2-xy+y^2)
x^3+y^3=(1)(4-xy)
----------
(x+y)^2=x^2+2xy+y^2
x^2+2xy+y^2=1
(4)+2xy=1
2xy=-3
xy=-3/2
---------
x^3+y^3=(1)(4-xy)
x^3+y^3=(1)(4-(-3/2))
x^3+y^3=(1)(4+3/2)
x^3+y^3=(1)(11/2)
x^3+y^3=11/2

Just btw that was from Slashing UK

He probably saw it as a normal Algebra question...