Qualification > Math

Pure math(p3)

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candy:
second part pleasee!

The value of 'a' is 8

sahrhp:
SEE EARLIER PAGE 2

louis:
One way to get the other factor of  (x^4) -2x³-2x² +8  is doing the long division. 
 Divided by x² – 4x + 4 ,  you  get x² + 2x + 2

  Now,  (X^4 )- 2x³-2x² +8  =( x ²– 4x + 4)( x² + 2 x + 2)
                                     =(  x – 2 ) ² {   ( x + 1 ) ² + 1 }
(  x – 2 ) ² is always positive
( x + 1 ) ² + 1 is always positive too.
So (X^4 ) -2x³-2x² +8  cannot be negative

crucio:
another rather tricky way of doing it is:




second derivative=
putting values of x in second derivative:




 hence there is a min point at -0.5 and 2 and max at 0, putting these values of x gives values of min points (-0.5, 7.8) and (2, 0), therefore as none of y values are below x axis, is always positive!  :D

SGVaibhav:
this is an A level thread, hmm, i was thinking that why dont i even know the head and tail of this.

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