TI-M: I think you're a weenie!!!
[Prev][Next][Index][Thread]
TI-M: I think you're a weenie!!!
> Besides
> there is a legal (hopfully!) way to do it.
Legal? haha, this is far from it:
> divide by x
> divide by x again
You can't do that - you're eliminating a root! In fact, you're actually
eliminating TWO roots of zero over the course of this problem. I'm amazed
that you can be doing calculuse without knowing this. It can give you many,
many wrong answers.
Other common mistakes along the same vein: multiplying both sides by a
variable or raising both sides to the same power, which is technically legal
but you must check to make sure you haven't created any extraneous roots
afterwards. If you're raising them to a fraction power (that include square
root) and the denominator is even, then you must allow one side to be either
its current value or the opposite of that (ie, plus or minus).
What you CAN do is factor both sides and get them equal to zero so you can
find the root. To take over from the last correct step in your work:
> x^2+2x=2x^2+2X
x^2+2x-2x^2-2x=0
-x^2=0
(-1)(x)(x)=0
(x)(x)=0
what you wind up with is two roots of zero. Were you to graph it, you
should get an inverted parabola whose vertex touches the x-axis at x=0.
-Scott
References: