Posted by Jon on .
Find the exact solution to 6x^2+1=8x by using the Quadratic Formula.
A)4+(sqrt10)
B)4+(sqrt22)/6
C)2+2(sqrt10)/3
D)4+(sqrt10)/6
I chose C
x=b+(sqrtb^24ac)/2a
x=8+(sqrt8^24(6)(1))/2(6)
x=8+(sqrt6424)/12
x=8+(sqrt40)/12
x= C

Math 
Reiny,
correct

Math 
drwls,
In the first one a = 6, b = 8 and c = 1
x = [8 +sqrt (6424)]/12
=[8 +sqrt(4*10)]/12
=[8 +2sqrt(10)]/12
=[4 +sqrt10]/6
So your amswer is wrong. 
Math 
Reiny,
Thanks for picking up on that
As George would have said,
"I guess I mislooked" 
Math(im confused) 
Jon,
Please explain x = [8 +sqrt (6424)]/12
=[8 +sqrt(4*10)]/12 
Math 
drwls,
64  24 = 40 = 4*10

Math(so how is my answer wrong? 
Jon,
i don't understand

Math 
drwls,
Which don't you understand:
6424 = 40, or
40 = 4 x 10?
Or my use of * for x when multiplying?
We do that often here to avoid confusion with the algebraic variable x. 
Math(please explain b/c I don't think im wrong) 
Jon,
I did all the steps

Math 
Damon,
a = 6
b = 8
c = 1
why did you use 8 for b?
why dis you not divide b by 2a?
you left a bracket out, wrecking everything
x = [ 8 +/ sqrt (64  4*6*1) ] /2*6
x = [ 8 +/ sqrt(6424) ] / 12
x = [ 8 +/ sqrt (4*10) ] /12
x = [ 8 +/ 2 sqrt (10) ] / 12
x = [ 4 +/ sqrt(10) ] / 6
I agree with drwls :)