How do you solve \sqrt { x - 3} = \sqrt [ 4(x + 4)] - 1x3=4(x+4)1?

1 Answer
Oct 15, 2017

No real solutions.

Explanation:

sqrt(x-3)=sqrt(4(x+4))-1x3=4(x+4)1

Since we cannot get rid of the 11, let's square and see what we get.

(sqrt(x-3))^2=(sqrt(4(x+4))-1)^2(x3)2=(4(x+4)1)2

x-3=(sqrt(4(x+4)))^2-2*sqrt(4(x+4))*1+(1)^2x3=(4(x+4))224(x+4)1+(1)2

x-3=4(x+4)-2sqrt(4(x+4))+1x3=4(x+4)24(x+4)+1

x-3=4x+17-2sqrt(4(x+4))x3=4x+1724(x+4)

2sqrt(4(x+4))=3x+2024(x+4)=3x+20

Now, let's square again.

(2sqrt(4(x+4)))^2=(3x+20)^2(24(x+4))2=(3x+20)2

4*4(x+4)=(3x)^2+2*(3x)*20+20^244(x+4)=(3x)2+2(3x)20+202

16x+64=9x^2+120x+40016x+64=9x2+120x+400

9x^2+104x+336=09x2+104x+336=0

Before we use the quadratic formula, let's check the discriminant to see if there are real solutions. If b^2-4acb24ac is less than 00, then there are no real solutions; if 00, there is only 11 solution; if greater than 00, there are 22 solutions. You can analyze the quadratic formula to see why this is the case.

(104)^2-4*9*336(104)249336

=-1280=1280

Thus, there are no real solutions.