Answer:
y=2 y=-8
Step-by-step explanation:
y^2+6y-16=0
this is a quadratic equation
we are going to factor as you have mention you want it solved with factorization;
The first term is,  y2  its coefficient is  1 .
The middle term is,  +6y  its coefficient is  6 .
The last term, "the constant", is  -16  
 Multiply the coefficient of the first term by the constant   1 • -16 = -16 
Find two factors of  -16  whose sum equals the coefficient of the middle term, which is   6 .
-2+8 = 6
 Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -2  and  8  
                     y^2 - 2y + 8y - 16
 Add up the first 2 terms, pulling out like factors :
                    y • (y-2)
 Add up the last 2 terms, pulling out common factors :
                    8 • (y-2)
 Add up the four terms 
 (y+8)  •  (y-2)
  Which is the desired factorization
y=2 y=-8
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