SOLUTION: how do you solve {{{ sqrt(2x)= x-4 }}}

Algebra.Com
Question 395017: how do you solve
Found 2 solutions by ewatrrr, jsmallt9:
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!

Hi, Note correction of middle term of trinomial**
solving
|squaring both sides
2x = (x-4)^2
2x = x^2 - 8x + 16
x^2 -10x + 16 = 0 |**
factoring
(x-8)(x-2) = 0
(x-8)= 0 x = 8
(x-2) = 0 x = 2 Extraneous solution
x = 8
Answer by jsmallt9(3758)   (Show Source): You can put this solution on YOUR website!
Another tutor's solution is mostly correct. But there is a mistake.

Square both sides:


(Subtracting 2x from each side (this is where the mistake was made):

Factor:
(x-2)(x-8) = 0
From the Zero Product Property we know that this (or any) product can be zero only if one (or more) of the factors is zero. So:
x-2 = 0 or x-8 = 0
Solving these we get:
x = 2 or x = 8

Whenever you square both sides of an equation extraneous solutions may be introduced. Extraneous solutions are solutions that fit the squared equation but do not fit the original equation. These extraneous solutions can occur even if no mistakes have been made! For this reason you must check your answers any time you square both sides of an equation.

When checking, always us the original equation:

Checking x = 2:


Check failed! This is an extraneous solution and must be rejected.

Checking x = 8:


Check!

So the only solution to your equation is x = 8.

RELATED QUESTIONS

how do you solve the following: {{{sqrt(x+4)}}} + {{{sqrt(2x-1)}}} = {{{sqrt(7x+1)}}} (answered by tracyc0912,Edwin McCravy)
HOW DO YOU SOLVE... (answered by solver91311)
Solve. {{{sqrt(x-1)+sqrt(x-4)=sqrt(2x-1)}}} (answered by jim_thompson5910)
How do you solve: {{{ 4^(x-4)=0.5^(5-2x)... (answered by jim_thompson5910)
How do I solve the follwoing system of equations? y = {{{ sqrt (x) }}}+ 4 y = 2x + 1 (answered by jim_thompson5910,Alan3354)
how do you solve 5/6x - 8/2x =... (answered by edjones)
How do you solve... (answered by rfer)
how do you solve x-2/4=... (answered by lwsshak3)
how do you solve this?Find x 2x+4=8 (answered by Alan3354,Jessica789)