Question 21?

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2 Answers
Jane
Mar 6, 2018

#B#

Explanation:

For a stationary point,

#(d(g(x)))/(dx)=0#

now, #(d(g(x)))/(dx)=27x^2-36=0#

or, #x=_-^+2/sqrt(3)#

Jim G.
Mar 6, 2018

#x=2/sqrt3toB#

Explanation:

#"to find the x-coordinate of a stationary point"#
#"differentiate and equate to zero"#

#g(x)=9x^3-36x+35larr" differentiate using power rule"#

#rArrg'(x)=27x^2-36#

#"for stationary points let "g'(x)=0#

#rArr27x^2-36=0#

#rArr9(3x^2-4)=0#

#rArr3x^2=0+4=4#

#rArrx^2=4/3#

#color(blue)"take the square root of both sides"#

#rArrx=+-sqrt(4/3)=+-sqrt4/sqrt3=+-2/sqrt3#

#"the required x-coordinate is "x=2/sqrt3toB#

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