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# Help. ​

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Help.

NotSoSmart  Feb 1, 2018
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#1
+82863
+1

10.

(8a-3)-2/3   =   8-2/3  *   (a-3)-2/3

Note, NSS.....

a-m   =   1 / am           and       ( am )n    =  am * n

So we have

1 / 82/3    *   a6/3

And  we can write

1 / 3√ [ 8 2 ]     *  a2

1 / 3√64  * a2

1 / 4  * a2

a2 / 4

CPhill  Feb 1, 2018
#2
+82863
+1

9.  We want to multiply top/bottom by the congugate of 2 - √5 ⇒  2 + √5

2 + √5        (2 + √5)

_____

2 -  √5        (2 + √5)

Let's do these separately

( 2 + √5 )  ( 2   + √5)  =

2(2)  + 2√5 + 2√5  +  √5*√5  =

4 + 4√5 + 5 =

9 + 4√5        (1)

( 2 - √5 )  ( 2   + √5)  =

2(2)  - 2√5 + 2√5  -  √5*√5  =

4 - 5 =

-1      (2)

Put  (1)  over (2)  and we have

[ 9 + 4√5 ]                      -9  - 4√5

________       =

-1

CPhill  Feb 1, 2018

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