I'm trying to solve 2x^2+11x-21 by quadratic formula. Factoring gives 3/2, -7, but by the formula (which should always work), I get: (-11/4)+/-((22/4)(42)^(1/2)). Can anyone help me spot my stupid error?

Question

I'm trying to solve 2x^2+11x-21 by quadratic formula. Factoring gives 3/2, -7, but by the formula (which should always work), I get:  (-11/4)+/-((22/4)(42)^(1/2)). Can anyone help me spot my stupid error?

lalaly · Answer

are u still there?

anonymous · Answer

factoring gives 3/2, -7, the quadratic formula is x=(-b±sqrt(b^2-4ac))/2a
from your equation a=2,b=11,c=-21
put values in formula  x=(-11±sqrt(121-(168)))/2x2
x=(-11±sqrt(289))/4
x=(-11±17)/4.
x=3/2, -7

jhonyy9 · Answer

so if factoring this is right (2x-3)(x+7)=2x2+11x-21 so than your got solutions x=3/2 and x=-7 is right,correct sure always

jhonyy9 · Answer

mominanisar ATTENTION in this calcules are some errore because inside squarroot there not is minus 168 correct,right is plus 168 and in thgis way will get these correct factorized resultes

jhonyy9 · Answer

check it newly please

anonymous · Answer

i am seriously sorry actually this step is likex=(-11±sqrt(121-(168)))/2x2
 new onex=(-11±sqrt(121-(-168)))/2x2
because 'c' is  minus

anonymous · Answer

it is a typing mistake by me

anonymous · Answer

Thanks!