Solve to equation, 2x^2-x-1=0, using the quadratic formula. a. x=-1 or x=-1/2 b. x=-1 or x=2 c. x=1 or x=-1/2 d. x=1 or x=1/2

C

for the quadratic 2x² - x - 1 = 0 ← in standard form

with a = 2, b = - 1 and c = - 1 , then

x = (1 ± √( 1 + 8 )) / 4 ← quadratic formula

  = ( 1 ± ) / 4

  = ( 1 ± 3 ) / 4

x = or x =

x = = 1 or x = = -