latex – Can not render quicklatex images?

[latex] [+preamble] usepackage {amsmath} [/preamble]

begin {align *} f (x) & = e ^ { sqrt {cot ~ x}} f (x + h) & = e ^ { sqrt {cot (x + h)}} \ dfrac { d} {dx} f (x) & = lim_ {h to0} ~ dfrac {f (x + h) -f (x)} {h} & = lim_ {h to0} ~ dfrac {e ^ sqrt {cot (x + h)} – e ^ sqrt {cot ~ x}} {h} & = lim_ {h to0} ~ e ^ sqrt {cot ~ x} ~. dfrac {e ^ { sqrt {cot (x + h)} – sqrt {cot ~ x}} – 1} {h} & = lim_ {h to0} ~ ee \ sqrt {cot ~ x} ~. Bigg ( dfrac {e ^ { sqrt {cot (x + h)} – sqrt {cot ~ x}} – 1} { sqrt {cot (x + h)} – sqrt {cot ~ x} } Bigg) times dfrac { sqrt {cot (x + h)} – sqrt {cot ~ x}} {h} hspace {1cm} Bigg[Since,~lim_{xto0}~dfrac{e^x-1}{x}=1Bigg] & = lim_ {h to0} ~ e ^ sqrt {cot ~ x} ~. dfrac { sqrt {cot (x + h)} – sqrt {cot ~ x}} {h} & = lim_ {h to0} ~ e ^ sqrt {cot ~ x} ~. dfrac { sqrt {cot (x + h)} – sqrt {cotx}} {h} times dfrac { sqrt {cot (x + h)} + sqrt {cot ~ x}} { sqrt {cot (x + h)} + sqrt {cot ~ x}} hspace {1cm}[Rationalising~the~numerator] & = lim_ {h to0} ~ e ^ sqrt {cot ~ x} ~. dfrac {{cot (x + h)} – {cot ~ x}} {h times ({ sqrt {cot (x + h)}} + sqrt {cot ~ x})} & = lim_ { h to0} ~ e ^ sqrt {cot ~ x} ~. dfrac { dfrac {cot ~ (x + h) ~ cot ~ x + 1} {cot ~ (x + hx)}} {h times ({ sqrt {cot (x + h)}} + sqrt {cot ~ x})} hspace {1cm} Bigg[cot~(A-B)=dfrac{cot~A~cot~B+1}{cot~A-cot~B}Bigg] & = lim_ {h to0} ~ e ^ sqrt {cot ~ x} ~. dfrac { dfrac {cot ~ (x + h) ~ cot ~ x + 1} {cot ~ h}} {h times ({ sqrt {cot (x + h)}} + sqrt {cot ~ x })} & = lim_ {h to0} ~ e ^ sqrt {cot ~ x} ~. dfrac {{cot ~ (x + h) ~ cot ~ x + 1}} {{cot ~ h} times {h} times ({ sqrt {cot (x + h)}} + sqrt {cot ~ x})} & = lim_ {h to0} ~ e ^ sqrt {cot ~ x} ~. dfrac {{cot ~ (x + h) ~ cot ~ x + 1}} { dfrac {h} {tan ~ h} times ({ sqrt {cot (x + h)}} + sqrt {cost ~ x})} & = lim_ {h to0} ~ ee sqrt {cot ~ x} ~. dfrac {{cot ~ (x + h) ~ cot ~ x + 1}} {dfrac {h} { dfrac {tan ~ h} {h} times {h}} times ({ sqrt {cot ( x + h)}} + sqrt {cot ~ x})} hspace {1cm} Bigg[Since,~lim_{hto0}~dfrac{tan~h}{h}=1Bigg] & = dfrac {e ^ { sqrt {cot}} times (cot ~ x ^ 2 + 1)} {2 sqrt {cot ~ x}} hspace {1cm} Bigg[Since,~(1+cot^2~x=cosec^2~x)Bigg] & = dfrac {e ^ { sqrt {cot}} cosec ^ 2 ~ x} {2 sqrt {cot ~ x}} end {align *}

[/latex]

do not know why quicklatex not able to render images?