Solve the equation using factoring or the quadratic formula, whichever is appropriate. 0.02y^2+0.06y-0.07=0

Question

Solve the equation using factoring or the quadratic formula, whichever is appropriate.  0.02y^2+0.06y−0.07=0

Answer 1

I believe one of the roots is -1.5 + 0.5 times the square root of 23. This is very close to 0.9

Answer 2

 

     0.02y^2+0.06y-0.07=0
 
First of all, understand the multiplicative property of zero:  multiply any number by 0 and get 0.
 
  2y² + 6y - 7 = 0                (note: 100*0 = 0)
 
Then think about F-O-I-L:
    (ax + b)(cx + d)  = acx2 + adx + bcx + bd  =  acx2 + (ad+bc)x - bd
  and let a=1,
    then since ac=2, c=2
  also,
      ad+bc=6,

         so d+2b=6   and   bd=-7
    That mean that this equation is not simple to factor,

 

so use the Quadratic Formula (use original a, b, c now: ax² + bx + c) with a=2, b=6, c=-7.