# New TI nspire CAS

• Oct 13th 2009, 09:19 AM
bitnibbler
New TI nspire CAS
Hello,

I was wondering if someone could help me with a problem I am having with my nspire cas calculator. When I try to factor a perfect square trinomial like factor(4x^2 -36xy + 81y^2) it returns the following answer 4x^2+9(9y^2-4xy) instead of (2x-9y)^2, which is what the book that I am reading says it should be. I don't think that it is a calculator issue. I am more inclined to believe the problem is with me.

Thanx,

Jim
• Oct 13th 2009, 09:24 AM
Chris L T521
Quote:

Originally Posted by bitnibbler
Hello,

I was wondering if someone could help me with a problem I am having with my nspire cas calculator. When I try to factor a perfect square trinomial like factor(4x^2 -36xy + 81y^2) it returns the following answer 4x^2+9(9y^2-4xy) instead of (2x-9y)^2, which is what the book that I am reading says it should be. I don't think that it is a calculator issue. I am more inclined to believe the problem is with me.

Thanx,

Jim

The TI 89 will do the same thing if you input that expression into it.

The issue is this: its treating xy as a variable, instead of the product of two variables.

To fix that, type in (4x^2-36x*y+81y^2) and it should give you the desired result.
• Oct 13th 2009, 10:07 AM
bitnibbler
Thank you for posting a response. If I read your suggestion correctly, it was to place a multiplication symbol between the x and y of the second term. I gave it a go and it did the same thing. I did notice that the nspire always expands the equation out inserting multiplication symbols where it thinks they should go. I appreciate the help though.

Jim
• Oct 13th 2009, 11:03 AM
bitnibbler
What I find odd is that it works on the CAS software running on my vista box but not the calc. (Itwasntme)