How do you solve using the quadratic formula #5x^2-8x-14=0#?

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Answer 1 · 2015-05-10T18:55:28

#5x^2-8x-14=0# is of the form #ax^2+bx+c=0#, with #a=5#, #b = -8# and #c = -14#.

The quadratic formula gives #x = (-b +-sqrt(b^2-4ac))/(2a)#.

So substituting our values for #a#, #b# and #c#, we get:

#x = (8+-sqrt(8^2-4*5*(-14)))/(2*5)#

#= (8+-sqrt(4*16+4*70))/10#

#=(8+-sqrt(4*86))/10#

#=(8+-sqrt(4)*sqrt(86))/10#

#=(8+-2*sqrt(86))/10#

#=(4+-sqrt(86))/5#

#=4/5+-sqrt(86)/5#