Originally Posted by

**aargh27** And theres another problem..

dont remember how its worded but it wants the minimum of the sum of two positive numbers, where the first is ^3 and the second is ^2. Also, they, without the ^, = 4

so

X+Y=4

Y= (-x+4)

X^3 + (-x+4)^2 -> X^3 + X^2 -8X +16

F'= 3x^2 + 2x -8

and after using -b plus/minus (Radical b^2 (-4)(a)c) divided by 2a

the x's are .. 1.33333333333etc and .. -2 i think

and the 1.3333333333333 comes to be the min because after plugging it into f" = 6x +2 it is a Positive concave,

so 1.3333333333 being x, i'd put it into f' to find the y, which comes to be.. around 9.45 or something similar,

and putting that into the origional equation, (1.33333333^3) + (9.45^2) = around 95 or a high number like that

HOWEVER this MUST be wrong because 9.45 + 1.3333 does NOT = 4

Where did i mess up on this one?