Use the quadratic formula to solve the equation. if necessary, round to the nearest hundredth. −6y^2 − 9y = −1 a, –9.5, 8 b, –0.1, 1.6 c, –3.21, 0.21 d, –1.6, 0.1

It is usually nicer to work with positive numbers, so add the opposite of the left side of the equation.
  0 = 6y² + 9y -1
You identify a=6, b=9, c=-1 for the quadratic formula, which tells you
  y = (-b ±√(b²-4ac))/(2a)
  y = (-9 ±√(9²-4(6)(-1)))/(2·6)
  y = (-9 ±√105)/12
  y = -1.60, 0.10

The appropriate choice is
  D, -1.6, 0.1

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You don't really need to solve the equation if you can test the offered solutions. Dividing by the coefficient of y², your equation becomes
  y² + (3/2)y - (1/6) = 0
This tells you the sum of the roots will be -3/2 (the opposite of the y coefficient), and their product will be -1/6 (the constant term). Selections A and C have the wrong product; selection B has the wrong sum.

Where’s the problems ? ?