solve using the perfect square factoring patterns: y^2 + 18y + 81 = 0

Question

nurali · Answer

y^2 +18y +81 = 0
 
Again rudimentary knowledge of time tables should tell you we're dealing with the number 9.
 
9+9 = 18, 9*9 = 81
 
The equation says +18y and +81 so clearly the sign has to be positive.
 
(y+9)^2 = 0
 
(y+9) = square root of 0
 
Ok this is going to break with normal quadratic equations as it will only have one solution, when we square root zero, we get +ve 0 and -ve 0 but they both mean zero.
 
(y+9) = 0
 
y= -9

anonymous · Answer

answers
a)9
b)9, -9
c)-9
d)0, -1

anonymous · Answer

ok thank you

nurali · Answer

Anytime