Use quadratic formula

[Guest]

Solve using quadratic formula

a. 8x -26x +20 = 0
b. 8x²-72 = 0
c. 2x² -3x -1 = 0


I'm horrible at Maths, I'm clueless as to how to solve these. I would luv to understand how to work these

[Guest]

[tex]8x^2 - 72 = 0[/tex]
[tex]8x^2 = 72[/tex] divide the both sides by 8.
[tex]x^2 = 9[/tex]
[tex]x = \pm 3[/tex]

If you would like to solve the equation by using the quadratic formula b=0, a=8, c=72
D=4*8*72

[Guest]

Yes, you will probably need the quadratic formula to solve the first and third equations; the solutions do not come out to nice round numbers.

Have you covered the Quadratic Formula?
There is a lot of material online about this formula. Two of my favorite math sites for general concepts are Wikipedia and Mathworld.

There are also many online tools for computing numerical solutions. For example, the following page is quite handy:

Quadratic Equation Solver

Hope this helps.

[Math Tutor]

Here is a great quadratic equation solver

[Guest]

Here is a great quadratic equation solver

If it is so great, why doesn't it solve for complex roots? I tried the simplest quadratic equation I could think of, but it did not work: a = 1, b = 1, c = 1

The explanation of quadratic roots is a nice touch but, to be thorough, it should be able to solve for complex solutions.

[Guest]

A much better way to calculate quadratic equations as well with real roots as with complex ones. And many other things, too.

http://www.wolframalpha.com/

[qamath08]

a. 8x -26x +20 = 0
for this first take 2 as multiple i.e., 2(4x-13x+10)=0
send 2 to that side therefore 4x-13x+10=0

no factors for this, so go for formula (-b+ -\sqrt{b2-4ac})/2a

b. 8x²-72 = 0
8x^2=72
x^2=72/8
x^2=9
x=+ or - 3

c. 2x² -3x -1 = 0

2x^2-3x-1=0

no roots for this go by formula stated in the above

[Guest]

Thank you for the detailed solutions.