Is there a positive/negative sign all in one on the ti-84? like to use for the quadratic formula... -b (plus or minus[symbol here?]) the square root of... the rest

Hi rayalak857,

Have a nice day.


Calculator does not have a solve program, but you can use it to solve the quadratic equation with a little effort. If you know the theory skip toward the end.
Here is the example:

Let aX^2+bX+C=0
1. First calculate the discriminant usually called Delta and given by
Delta =b^2 -4*a*c store the value in the variable D
If Delta is positive you have two roots X1 and X2 given by
X1=(-b+square root of Delta)/(2*a)
X2=(-b- square root of Delta)/(2*a)

If Delta is equal to 0, X1=X2=-b/(2*a)
If Delta i negative, no real solutions exist

You only solve if Delta is positive or equal to 0.

Putting in the values of a, b, and c
value of a (put you number) [SHIFT][STO] A
value of b (put your value) [SHIFT][STO] B
value of c (put you value) [SHIF][STO] C

[ALPHA] B [X^2] -4[x][ALPHA] A [x][ALPHA] C [=]
Value of delta is displayed. If it is positive, you store its square root in D

[Square root] [ANS] [SHIFT][STO] D ;

Calculate 1/(2*a) and store in variable F
1./(2[x] ALPHA A) [SHIFT][STO] F

To obtain X1
[ALPHA] F [x] ( (-) ALPHA B + ALPHA D ) [=]
To obtain X2
[ALPHA] F [x] ( (-) ALPHA B - ALPHA D ) [=]

Be careful: the (-) is the change sign not the regular minus sign.

Hope it helps. Goodluck

Thank you for using fixya.

Press the "2ND" key at the upper-left-hand corner of the keyboard to access the second functions. For example, to calculate the square root of 2, press 2ND [square-root] 2 ENTER.

Two ways:

2ND [square-root] ( 8 7 . 3 4 / 5 ) ENTER

8 7 . 3 4 / 5 ENTER then 2ND [square-root] 2ND ANS ENTER

The first sequence takes the square root of 87.34/5, the second sequence calculates 87.34/5 then takes the square root of the result.

Use the (-) key next to the decimal point key to enter the negative sign, not the - key. The (-) key is for negative values, the - key is for subtracting one value from another.

You're both right, in a way. (-64)^3 is -262144. The square root of that is +/- 512i. Take your choice as to the sign.

For what it's worth, the TI-84, TI-86, TI-89, and the HP 50g all go with the negative value.

Hello,
The calculator has two minus signs

1. The regular MINUS sign which is used with the subtraction operation. This operation is binary, requiring two operands (two terms). In a-b, a and be are the operands (they very specific names, but I will skip this detail).
   
2. The negation or change sign. This operation is called unary, requiring one operand. -a means take the negative of the number a.

These are the technicalities, in which you may not be interested. On calculators, the two operations are implemented differently, with two signs, the regular minus sign -- , and the change sign (-) usually smaller in size than the regular -- sign and raised above the main line.

Examples. Let (-) be the negation and -- the regular minus.

• If you enter (-) 12 the TI84Plus accepts it and calculates the negative of 12.
• If you enter 12 (-) 13 the TI protests with a syntax error
• If you enter 12 ( (-) 13) the calculator interprets it as 12* (-13) and calculates -156.
• If you enter --12, the calculator displays Ans--12, where Ans is the last result calculated. If Ans happens to be 0, the new result is obviously the one you are expecting. But if Ans holds a non zero value, this is incorrect.

Suppose you have to calculate X^(-2)*X^(-1/3)
You can enter it exactly as it is written above. In this case, you must use the change sign (-) in both factors.
You can also decide to use the power rules and enter the expression as X^( -2 --1/3). In this case the first minus is the negation and the second is the regular minus.

I could go on with a few more examples, but that will take us away from your present concern.

In short.

1. If the minus sign is the leftmost (first) symbol in your function (after the Y1=) you should use the negation. Any subsequent minus should be the regular minus --
2. If the minus sign is the first symbol in an exponent, you must use the negation. Any subsequent minus in the expression of an exponent should be the regular minus --

I hope it did not bore you death with details you do not care to know about. I do hope that it will help you prevent this type of syntax errors.

Do not forget to rate the solution

Hello,
I am not sure what the cross (x) means: is it a multiplication or the variable x, so I took a screen capture of both cases.

The top case is obtained as follows the asterisk is the multiplication sign to thr right of digit 9; the small minus is the change sign key the minus sign in parentheses under digit 3 and to the left of ENTER key.; the forward slash is the division sign, above the multiplication sign.
This small minus called change sign makes a positive number negative and a negative number positive, hence its name. If your expression starts with a negative sign that is the one to use. Use it also for negative exponents.

As you can see the result is -.8. Notice how the - before the dot is small with respect to the regular minus, as in the last expression.

For the last expression on the screen capture, there is nothing special, except that you have two ways to enter the variable X.

1. Press [ALPHA] [STO->]
2. Press the key [X,T, Theta, n] to the right of the green [ALPHA] key.

Hope it helps.



If x is the multiplication sign
8[x] [(] (-)1

Hello,
The calculator does not have a solve program, but you can still use it to solve the quadratic equation with a little effort. If you know the therory skip toward the end.

Let aX^2+bX+C=0
1. First calculate the discriminant usually called Delta and given by
Delta =b^2 -4*a*c store the value in the variable D
If Delta is positive you have two roots X1 and X2 given by
X1=(-b+square root of Delta)/(2*a)
X2=(-b- square root of Delta)/(2*a)

If Delta is equal to 0, X1=X2=-b/(2*a)
If Delta i negative, no real solutions exist

You only solve if Delta is positive or equal to 0.

Putting in the values of a, b, and c
value of a (put you number) [SHIFT][STO] A
value of b (put your value) [SHIFT][STO] B
value of c (put you value) [SHIF][STO] C

[ALPHA] B [X^2] -4[x][ALPHA] A [x][ALPHA] C [=]
Value of delta is displayed. If it is positive, you store its square root in D

[Square root] [ANS] [SHIFT][STO] D ;

Calculate 1/(2*a) and store in variable F
1./(2[x] ALPHA A) [SHIFT][STO] F

To obtain X1
[ALPHA] F [x] ( (-) ALPHA B + ALPHA D ) [=]
To obtain X2
[ALPHA] F [x] ( (-) ALPHA B - ALPHA D ) [=]

Be careful: the (-) is the change sign not the regular minus sign.

Hope it helps.

I think you are using the minus symbol instead of the negative symbol (located below the 3).

I'm assuming you want the +/- symbol like you see in the quadratic formula. There is no key to enter this. You will have to enter 2 separate problems. Enter the numbers with the + symbol and then enter the numbers with the - symbol.