what does y equal in the equation: y^2+4y=87

Question

y²-1+4y+4=90 and I simplified it to y^2+4y=87

 what does y equal?

Answer 1

y² - 1 + 4y + 4 = 90

 

y² +4y  = 87 and solve by completing the square

 

y² + 4y + 4 = 87 + 4

 

(y + 2)² = 91

 

y+2 = +/- sqrt(91)

 

y = -2 +/- sqrt(91)