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# Sketching graphs watch

1. How would you sketch the graph f(x)= x^4-4x-8

i know that f(x) simplies to f(x)=(x-2)(x^3+2x^2+4x+4) but i have no idea how to sketch it . HELP SOMEONE !!!-
2. (Original post by maxfire)
Here.

but how would i know to sketch it like that in an exam???
3. Construct a table of values?
4. basically. the general rules are

set x = 0 look at what happens to f(x) (y-axis crossing point)
set f(x) = 0 (not always possible/easy) and see what x needs to equal (x-axis crossing points)
mark the all the crossing points you can work out on an axis.

differentiate it to find the turning points. mark these on the graph aswell

then look what happens as x tends to infinity and -infinity

then pretty much join up the dots, and make sure you have the graph doing the correct things towards infitinity and - infinity

(obviously there is more to it depending on the function, asymptotes etc)
5. (Original post by klgyal)
How would you sketch the graph f(x)= x^4-4x-8

i know that f(x) simplies to f(x)=(x-2)(x^3+2x^2+4x+4) but i have no idea how to sketch it . HELP SOMEONE !!!-
Factorise the x^3 bracket too, innit.

Also, if you really can't do it, table of values, when x = 0, y = ..., when x = 1, y = ..., plot.

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