Question 457450

{{{Y^2 -12Y + 36=81}}}

{{{Y^2 -12Y + 36-81=0}}}

{{{Y^2 -12Y-45=0}}}...use quadratic formula

{{{Y = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 


{{{Y = (-(-12) +- sqrt( (-12)^2-4*1*(-45) ))/(2*1) }}} 


{{{Y = (12 +- sqrt(144+180 ))/2 }}} 


{{{Y = (12 +- sqrt( 324 ))/2 }}} 


{{{Y = (12 +- 18)/2 }}}



solutions:

{{{Y = (12 +18)/2 }}}

{{{Y = 30/2 }}}

{{{Y = 15 }}}

or

{{{Y = (12 -18)/2 }}}

{{{Y = -6/2 }}}

{{{Y =-3 }}}