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+1
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avatar+2448 

Need help with a couple, also please correct me if i'm wrong

3. x=3y+2

-2 from both sides= x-2=3y

(3)x-2(3)=(3)3y=

y=3x-6

 

4. x=2/3y-5

+5 both sides

x+5=2/3y

(3/2)x+(3/2)5=(3/2)2/3y=

y=3/2x+7.5

 

5. x=y^2+8

-8 from both sides= x-8=y^2 (not sure what comes next) is it x-8^2=(y^2)^2 ???

 

6. x=(y+3)^2

Not sure what to do next for this one but I tried a little bit: x^2=((y+3)^2)^2=x^2=y+3 I don't know >.<

 Aug 21, 2018
 #1
avatar+98197 
+2

3.  f(x)  = 3x  + 2

Here's the way I learned it..... for  f(x), write "y".... get x by itself... "swap" x and y

 and for "y"  write f-1(x)  [this notation represents the inverse ]

 

So we have

y  = 3x+ 2

y - 2  = 3x

[y - 2] / 3  = x        "swap"  x and y

[x - 2 ] / 3  = y

[x -2 ] / 3  = f-1(x)

BTW....swapping x and y like you did in your first step is  OK, too.....!!

 

#4   looks good...!!!

 

Here's  the last two

 

f(x)  = x^2  + 8

y = x^2 + 8

y - 8  = x^2        take both roots

±√ [y -8] = x      swap  x and y

±√[ x - 8 ]  = y

±√[x - 8]  =  f-1(x)

 

 

f(x)  = (x + 3)^2

y = (x + 3)^2      take both roots

±√y = x + 3

±√y  - 3   = x      swap x and y

±√x  - 3   = y

±√x  - 3  =  f-1(x)

 

 

cool cool cool

 Aug 21, 2018
 #2
avatar+2448 
+2

Thank you, that's not quite how I learned it but maybe i'll get used to it being that way...

RainbowPanda  Aug 21, 2018

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