Question

If using calc. to input quadratic formula to solve
3x^2=-9/2x + 6
How would I key in?

Answer 1

Hi

Well, first put it in the standard form ax^2 + bx + c = 0

Then use the constants a, b, and c in the quadratic formula.

Answer 2

So I have:
a=3
b=9/2
c=-6

Answer 3

looks good so far

Answer 4

So, I can write it out OK, but if i want to key it into calc do I have to use \[\pm\] or parenthesis around the 9/2?

Answer 5

usually the easiest thing to do is first compute what's in the radical, b^2 - 4ac.
Take the square root.

the +/- means you have two answers, one where you add that square root and one where you subtract it. Most calculators don't have a +/- key that does it automatically.

Answer 6

If I were using a regular calculator, I'd probably first compute 4 * a * c, which is -72. Then key in 9/2, then square that, then add 72 (which is the same as subtracting -72). Then take the square root.

Answer 7

I'm using TI-84, thought maybe I could plug it all together but that's just as easy

Answer 8

I've never used one. I actually use mathematica personally, which solves the whole thing for you instantly anyway just by typing in the original equation.

Answer 9

When I was in high school I used an old ti-35 which doesn't take complex expressions at all

Answer 10

Yeah...I'm doing literally dozens of these quadratic formulas and it's starting to make my head hurt

Answer 11

Thank you for the help

Answer 12

THere are lots of quadratic calculators on the web, where you just type in A, B and C and it computes it for you

Answer 13

For example, this one: http://www.math.com/students/calculators/source/quadratic.htm

Answer 14

You can program it into your calculator as well, the language is pretty intuitive and easy to use, but you might have to google the syntax first.