You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Quadratic problem
- Thread starter jman15
- Start date
jman15 said:I'm really bad at quadratic equations and have no idea to do this problem.
Solve for x: 2x^2-11x=13
please help :mrgreen:
This is pretty basic. If you have a tough time with problems like this possibly you should resort to using the quadratic formula. In the mean time let's look at the possibilities...
\(\displaystyle 2x^2-11x-13=0\)
Factors of the coefficient of the first term are +1 and +2. We need not consider -1 and -2.
Factors of the coefficient of the last term are only +1, -1, +13 and -13. We DO need to consider negatives here.
This leads to the following possibilities...
(1x+1)(2x+13) = 0
(1x-1)(2x+13) = 0
(1x+1)(2x-13) = 0
(1x-1)(2x-13) = 0
(1x+13)(2x+1) = 0
(1x-13)(2x+1) = 0
(1x+13)(2x-1) = 0
(1x-13)(2x-1) = 0
We could consider negative signs for the first term but bear in mind that
(-1x+1)(2x+13) yields a negative first term rather than a positive which we need, and (-1x+1)(-2x+13) = 2x[sup:21f2f8z7]2[/sup:21f2f8z7]-15x+13 which is the same as (1x-1)(2x-13).
Which one of the above works?
Well, solve it using the quadratic formula...show us what you can do :idea:jman15 said:I'm not 100% sure...
NO. Should be: (11 +- sqrt(225)) / 4jman15 said:Yes i did and i think i am doing it right now. the only thing... i worked it down to -11 plus or minus the square root 17 over 4
please tell me if this is right so far and how to do the rest
Like, since b = -11, then -b = 11 ; kapish?
NO. Look, I can't teach you basics from here!
Go here and LISTEN: http://www.youtube.com/watch?v=s80J2dAUUyI
Go here and LISTEN: http://www.youtube.com/watch?v=s80J2dAUUyI
YES! Was kinda kidding since you didn't seem to understand "-4ac" = -4 * 2 * -13 = 104.jman15 said:So should x equal 6.5 or -1
am i correct?
Hope that utube thing made it clear.