# Algebra

posted by .

Using +/- for plus or minus

*****************_________
Formula: -b +/- \/b^2-4ac
********____________________

*****************2a

Equation:

x^2 - 25 = 0

Books says answer is 5 and -5. I can get the 5. I do not get the -5.

• Algebra -

I don't understand.

Didn't you post the formula with a +/- ?

so in your equation x^2 - 25 = 0
a = 1
b = 0
c = -25

so x = (0 ±√(0-4(1)(-25))/2
= ±√100 / 2
= ±10/2
= ±5

of course the easier way would be to write the equation as
x^2 = 25 , then
x = ±√25 = ±5

• Algebra -

Yes I did post it with a +/- representing plus or minus the number.

How were you about to show the +- with the minus sign uder the the plus sign?

I looked at the answer you provided I think I can see my error. I was taking 0 for C not the 25. I remember now that C has to be a number without a variable next to it.

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