How would you solve this using the quadratic formula?

Question

3x^2-10x-10=0

I get x=4.13 and x=-0.81 when I enter this in my calculator
I think this problem requires you simpifly the radical once you input the values in the quadratic formula but I am unsure how to do that in this question to get the answer the calculator shows.

Answer 1

You are correct (depending on how accrate you want to be)


3x^2-10x-10=0

Discriminant = 100 +4(10)(3) = 220

x1 = (10 - sqrt(220))/6 = -0.805
x2 = (10 +sqrt(220))/6 =4.139

Answer 2

Hi: Being an old guy, I just remember how to do it by plugging the values into the formula for solving a quadratic (we didn't have calculators when I was a kid). Here's the formula for solving the quadratic ax^ + bx + c:

x = -b +/- sqrt(-b^ -4ac) all divided by 2a

This gives the 2 answers as 4.1386 and -0.8053

which is exactly what you have (after rounding).

I hope you can read my formula OK. Good luck.

Answer 3

x = [10 +/- sqrt((10^2-4(3)(-10))]/(2*3)
x = [10 +/-sqrt(220)]/6
x = [5 +/- sqrt(55)]/3
x = (5 +/- 7.4162)/3
x = 4.1387 and x = -.8054

Answer 4

you should get [10 (+/-) 220^(1/2)]/6