Re: Is the TI-92 worth the cost?

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Re: Is the TI-92 worth the cost?

On Tue, 4 Nov 1997, Casper wrote:
) I have included a program i wrote called CALC that does Limits and
) Quadratic Formula.
Erm, wherefore would you write something to do the quadratic formula for
you? It would be easiest, in my opinion, just to enter in the equation and
then use the [SOLVER] feature of the TI-85 to solve it for you, as you can
have it solve for one of the coefficients if you know one of the roots and
the other two coefficients, etc.

quad1=(-B+[SQUAREROOT](B^2-4*A*C))/(2*A)
quad2=(-B-[SQUAREROOT](B^2-4*A*C))/(2*A)
[2nd][SOLVER]
[CLEAR]quad1
exp=quad1
 exp=
 B=2
 A=1
 C=-10
 bound={-1E99,1E99}
Fill out as shown, then place your cursor over the second exp and his
[SOLVE] and you'll see one of the roots (2.3166...).
Repeat with exp=quad2 and you'll find the other root (-4.3166...)

However, if you're using that to solve quadratic equations, why even
bother with the quadratic formula at all?
[2nd][POLY]
Order=2
 a2=A
 a1=B
 a0=C
[SOLVE]

To find the roots of, say, x^2+2x-10, you would to
[2nd][POLY]2[ENTER]1[ENTER]2[ENTER]-10[SOLVE]
a2x^2+a1x+a0=0
 a2=1
 a1=2
 a0=-10
and your TI-85 will happily tell you the roots of that equation are
 x1=-4.31662479036
 x2=2.31662479036

If you have 2x^3+5x^2-6, you would enter
[2nd][POLY]3[ENTER]2[ENTER]5[ENTER]0[ENTER]-6[SOLVE]
and your TI-85 will tell you the roots of that equation are
 x1=(-1.71720603876,.510726574408)
 x2=(-1.71720603876,-.510726574408)
 x3=(.934593877514,0)
meaning the roots are
x = -1.71720603876 + .510726574408i
x = -1.71720603876 - .510726574408i
x = .934593877514 + 0i (or just x = .934593877514)

If you have 5x^26+7x^25-9x^21+16x^19-... just go into [2nd][POLY] and
enter in the order of the equation (the highest exponent of x) and fill
in the coefficients.
order=26
a26x^26+...+a1x+a0=0
 a26=5
 a25=7
 a24=0
 a23=0
 a22=0
 a21=-9
 a20=0
 a19=16
...

) I will be updating the program as we progress into the year.
)
) Oh yes.. I also have other programs for the 85...
) One that is invaluable in Trig, One that adds vectors for Physics,
To find the resultant of two vectors, go into [2nd][MODE] then go down and
over to CylV and press [ENTER] then [EXIT].
Now enter in
[magnitude1<heading1]+[magnitude2<heading2]
where < is [2nd] and the comma key (just above STO> and below x2)
So, if you have an airplane heading due north going 300 kilometres per
hour, with a cross breeze heading at 4 degrees north of due east blowing
at 50 kilometres per hour, you would enter
[300<0]+[50<86]
and you'd get back
[307.559253173<9.333...
You can go into [2nd][MODE] and adjust the significant figures as needed
to be able to see the rest of the line, such as Fix 6
[307.559253<9.333122]
Which is about 308 kilometres per hour at a heading of about 9 degrees
east of due north.

)                                                                    and one
) that does Empirical Formula for Chemistry
)
) Please mail me at mailto://Professor@softhome.net if you would like a copy
) of these.

--
Daniel Reed <n@narnia.n.ml.org>
System administrator of narnia.n.ml.org (narnia.mhv.net [199.0.0.118])
He who asks is a fool for five minutes, but he who does not ask remains a
 fool forever. -- Chinese proverb
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