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√x + fourth root of x = 30

 

a) 11

b) 12

c) 13

d) 14

e) 15

Guest Dec 16, 2017
 #1
avatar+87309 
+2

x^(1/2)  +  x^(1/4)   = 30        subtract 30 from both sides

 

x^(1/2)   +  x^(1/4)  - 30    =  0     we can factor this directly as

 

[  x^(1/4 )  +  6  ]    [ x^(1/4)  - 5  ]   =  0

 

Settting both of these factors to 0  and solving for x, the first produces no solution

 

For the second, we have that

 

x^(1/4)  - 5  = 0     add 5 to both sides

 

x^(1/4)  = 5           take both sides to the 4th power

 

x  = 5^4   =    625

 

 

cool cool cool

CPhill  Dec 16, 2017

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