SOLUTION: What is the solution of the equation? 4(3-x)^4/3 - 5 = 59 A. –5, 11 B. 5 C. 11 D. –11

Algebra ->  Radicals -> SOLUTION: What is the solution of the equation? 4(3-x)^4/3 - 5 = 59 A. –5, 11 B. 5 C. 11 D. –11       Log On


   



Question 624702: What is the solution of the equation?
4(3-x)^4/3 - 5 = 59
A. –5, 11

B. 5

C. 11

D. –11

Found 2 solutions by Edwin McCravy, ewatrrr:
Answer by Edwin McCravy(20063) About Me  (Show Source):
You can put this solution on YOUR website!
4(3-x)^4/3 - 5 = 59
matrix%282%2C1%2C%22%22%2C4%283-x%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

Add 5 to both sides 

    matrix%282%2C1%2C%22%22%2C4%283-x%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C64%29

Divide both sides by 4

    matrix%282%2C1%2C%22%22%2C%283-x%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C16%29

Now we use the principle of fraction exponents to radicals matrix%282%2C1%2C%22%22%2CA%5E%28B%2FC%29%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C%28root%28C%2CA%29%29%5EB%29

    %28root%283%2C3-x%29%29%5E4%22%22=%22%2216

We use the principle of even roots, in this case 4th roots. When taking
even roots we must use ± on the right side. Now since 16 = 2·2·2·2 = 24,
then the 4th root of 16 is 2. So we have:

    root%283%2C3-x%29%22%22=%22%22%22%22+%2B-+2

Next to get rid of the cube root we cube both sides:

    %28root%283%2C3-x%29%29%5E3%22%22=%22%22%28%22%22+%2B-+2%29%5E3

    3-x = ±8

If we use the +

    3-x = 8
     -x = 5
      x = -5

If we use the -

    3-x = -8
     -x = -11
      x = 11

So we get two solutions -5, and 11.  We check to see if either one
is extraneous:

Checking x = -5,

matrix%282%2C1%2C%22%22%2C4%283-x%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

matrix%282%2C1%2C%22%22%2C4%283-%28-5%29%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

matrix%282%2C1%2C%22%22%2C4%283%2B5%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

matrix%282%2C1%2C%22%22%2C4%288%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

Write 8 as 2³

matrix%282%2C1%2C%22%22%2C4%282%5E3%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

Multiply the exponents to remove the parentheses:

4(24) - 5 = 59
4(16) - 5 = 59
64 - 5 - 59
    59 = 59

So -5 is a valid solution.

Checking x = 11:


matrix%282%2C1%2C%22%22%2C4%283-x%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

matrix%282%2C1%2C%22%22%2C4%283-%2811%29%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

matrix%282%2C1%2C%22%22%2C4%283-11%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

matrix%282%2C1%2C%22%22%2C4%28-8%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

Write 8 as 2³

matrix%282%2C1%2C%22%22%2C4%28%28-2%29%5E3%29%5E%284%2F3%29%29matrix%282%2C1%2C%22%22%2C%22%22-%22%22%29matrix%282%2C1%2C%22%22%2C5%29matrix%282%2C1%2C%22%22%2C%22%22=%22%22%29matrix%282%2C1%2C%22%22%2C59%29

Multiply the exponents to remove the parentheses:

4((-2)4) - 5 = 59
4(16) - 5 = 59
64 - 5 - 59
    59 = 59

So 11 is also a valid solution.

Solutions:  -5 and 11

Edwin

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 
Hi,
4(3-x)^4/3 - 5 = 59
(3-x)^4/3 = 16
%28%283-x%29%5E%284%2F3%29%29%5E%283%2F4%29+=+16%5E%283%2F4%29
(3-x) = 16^3/4 = %28root%284%2C16%29%29%5E3
(3-x) = 8
-5 = x