+0  
 
0
460
1
avatar

 

 

 

Help ASAP!

 Dec 3, 2016
 #1
avatar+129840 
0

10  * 6√x ≤   2 * 6 - √x   - 8     first....divide through by 2

 

5  * 6√x ≤     1   - 4          next.....multiply both sides by 6√x

 

5 * 6 2√x   ≤   1   -  4* 6√x      add 4* 6√x   to both sides....subtract 1 from both sides

 

5 * 6 2√x   +  4* 6√x  -1  ≤   0      let    6√x    = u   ..... so   6 2√x  =  u^2.......  and we have

 

5u^2  + 4u  -  1   ≤  0       factor

 

(5u  - 1) (u + 1)   ≤  0     set both factors to 0 and we have that

 

u  = 1/5      and u  = -1

 

If u =  -1    then    6√x  =  -1    which is impossible

 

If u  =   1/5   then    6√x  = 1/5

 

Taking the log of both sides, we have that

 

log [ 6 √x ]  = log (1/5)     and we can write

 

√x   log 6  = log (1/5)     divide both sides by log 6

 

√x  =  log (1/5) / log (6)  ≈   -0.8982444   ...but this is impossible because a positive root cannot have a negative evaluation

 

 

Thus......there are no [real ] solutions to this problem 

 

Wolframalpha confirms this :

 

 https://www.wolframalpha.com/input/?i=solve+10+%C2%A0*+6%5E%E2%88%9Ax%C2%A0%E2%89%A4+%C2%A0+2+*+6%5E(+-%C2%A0%E2%88%9Ax)+%C2%A0+-+8

 

 

 

cool cool cool

 Dec 3, 2016

3 Online Users

avatar