How do you solve #\sqrt { x - 3} = \sqrt [ 4(x + 4)] - 1#?

1 Answer
Oct 15, 2017

No real solutions.

Explanation:

#sqrt(x-3)=sqrt(4(x+4))-1#

Since we cannot get rid of the #1#, let's square and see what we get.

#(sqrt(x-3))^2=(sqrt(4(x+4))-1)^2#

#x-3=(sqrt(4(x+4)))^2-2*sqrt(4(x+4))*1+(1)^2#

#x-3=4(x+4)-2sqrt(4(x+4))+1#

#x-3=4x+17-2sqrt(4(x+4))#

#2sqrt(4(x+4))=3x+20#

Now, let's square again.

#(2sqrt(4(x+4)))^2=(3x+20)^2#

#4*4(x+4)=(3x)^2+2*(3x)*20+20^2#

#16x+64=9x^2+120x+400#

#9x^2+104x+336=0#

Before we use the quadratic formula, let's check the discriminant to see if there are real solutions. If #b^2-4ac# is less than #0#, then there are no real solutions; if #0#, there is only #1# solution; if greater than #0#, there are #2# solutions. You can analyze the quadratic formula to see why this is the case.

#(104)^2-4*9*336#

#=-1280#

Thus, there are no real solutions.