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function questions help?

The question is
If f(x)= x squared +3x -6

Write down an expression for f(2x)

And solve f(2x)=0

Is f(2x) simply multiplying the whole equation by 2 to get 2xsquared +6x-12?
And then I use the quadratic formula to work out the value of x?

thanks for any tips you can give!
Reply 1
Avatar for the bear
the bear
20
nooooooo :naughty:

f(2x) means replace x with 2x in the formula for f(x)

for instance if f(x) = (x)3 then f(2x) = (2x)3
What the bear said. Multiplying the whole equation by 2 would be 2f(x), not f(2x).
Reply 3
Avatar for zhzstudent
zhzstudent
OP
1
Original post by the bear
nooooooo :naughty:

f(2x) means replace x with 2x in the formula for f(x)

for instance if f(x) = (x)3 then f(2x) = (2x)3


thanks, so should it be 4xsqaured +6x -6?
Reply 4
Avatar for the bear
the bear
20
Original post by zhzstudent
thanks, so should it be 4xsqaured +6x -6?


yes...

have you tried using the [sup method for writing powers ?

to do x squared you type x2
Reply 5
Avatar for zhzstudent
zhzstudent
OP
1
Original post by the bear
yes...

have you tried using the [sup method for writing powers ?

to do x squared you type x2


i'm not quite sure what you mean...

x2 ?
Reply 6
Avatar for zhzstudent
zhzstudent
OP
1
Original post by zhzstudent
i'm not quite sure what you mean...

x2 ?


no worries, i understand it now ,after i sent out the reply, thanks for the tip!
Reply 7
Avatar for the bear
the bear
20
Original post by zhzstudent
no worries, i understand it now ,after i sent out the reply, thanks for the tip!


you could also try replacing sup with sub....

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