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Use the first derivative to determine where the function f(x)=6x^4+192x is increasing...
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`f'(x)=24x^3+192=0` dividing by 24:
`x^3+8=0` then `x=-2`
`f''(x)=3x^2` and `f''(-2)=12 >0`
Thus `x= -2` is a min. point, it means function decrease for `x< -2` and decrease for `x>2` assuming the value `y=-288` for `x=-2`
by the (1) we know has zero for `x= 0` and `x=-2 ^3sqrt(4)`
Posted by oldnick on April 14, 2013 at 1:11 AM (Answer #1)
Function is an increasing function if
`x+2>0 and x^2+4-2x>0`
since f is real function so ,only possible `x>2`
Thus function is increasing if `x in(2,oo)` and decreasing is `x in(-oo,2)`
Posted by pramodpandey on April 14, 2013 at 4:22 AM (Answer #2)
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