How do you solve #5x^2−8x−4=0# using the quadratic formula?

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Answer 1 · 2016-06-04T03:07:52

#x = 2#, #x = -2/5#

The quadratic formula states that given a quadratic equation

#ax^2 + bx + c = 0#

Its roots can be obtained using the equation below

#x = (-b +- sqrt(b^2 - 4ac))/(2a)#

#5x^2 - 8x - 4 = 0#

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

#=> x = (8 +- sqrt(64 + 80))/10#

#=> x = (8 +- sqrt(144))/10#

#=> x = (8 +- 12)/10#

#=> x = 20/10 => x = 2#
#=> x = -4/10 => x = -2/5#