Question 191751
sq  rt  (2x+11)  =  (x+4)

square  both  sides

(2x+11) =  (x+4)^2 =  x^2  +8x  +16

0=  x^2  +6x  +5

0 = (  x+5)  (x+1)

x=  -5,   and  x=-1      however

since  we  squared  we  MUST  check  both  answers

checking  x=  (-1)

( 2(-1) +11 ) ^1/2  =  (  (-1)  +  4  )
(9)^1/2  =3  =3    ok        therefore  x= (-1)  is  valid

checking  x=  (-5)

(  2(-5)  +11 )^1/2  =  (-5)  +4

(1)^ 1/2  =  -1

1 = -1     questionable       

while  (1)^1/2  does  equal (+1)  and  (-1)  

commonly  we  must  question  validity  of  x= (-5)