In Home screen press [F2: Algebra] then select [3:expand(]. The command echoes on main command line. Complete the argument by typing in (x-0.3)(x/2 plus 0.15) and close the right parenthesis of the expand( )function.
You can also use the identity (special product) (a-b)(a plus b)=a^2-b^2. It is not that clear here, but if you you factored out the 1/2 you will see it.
1/2*(x-0.3)(x plus 2*0.15)=1/2*(x-0.3)(x plus 0.3)= 1/2*(x^2-0.3^2)
The Ti 89 solves a lot of fraction problems by being in the right mode and, the use of several commands. One of my first problems here at Fixya was to find a solution for, "How do i convert a decimal answer to fractions prefferably with matrixes."
Here the problem was solved just by being in the EXACT mode.
Another fraction nightmare, so I thought was to solve for, "I want to solve a Binomial Theorem problem!" You have to go to the end of the problem but, I solved it just by the use of the expand command.
The best way to display fraction is in Pretty Print and, in the EXACT mode. Here is a small demonstration of the 3 mode setting in the Ti 89 and, the effect of each to the way a fraction is displayed.
This is a demonstration of the Ti 89 simplifying and, displaying in fractional form in the AUTO mode.
This is a demonstration of the Ti 89 making numbers proper and, displaying them in fractional form while in the EXACT mode.
This demonstration of the Ti 89 not even converting in fractional form and, displaying in the APPROX mode.
You should always use parentheses when entering equations or, fractions into the calculator. Pictured just below you can see how the Ti 89 can miss-interpret what is being entered.
The propFrac command is a great tool to reducing to the simplest form.
propFrac(expression,var). This will return an expression as a
proper expression
Sometime with joining or, combining fractions you have to get the common denominator. As you can see below the comDenom command is a great tool for that.
The Ti 89's ability to compute fractions is only limited to the ability and, knowledge of the person using it. Even though, it has a tendency of making a not so, mathematically inclined person look like they have been doing them all there life.
I just gave several ways I go about solving and, displaying fractions. The best way to display fraction is in Pretty Print and, in the EXACT mode. Sometimes that isn't even enough and, you have to use parentheses and, commands to do the job.
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