Consider the function $f(x,y)=2sin(7x-4y)$ and the point $P(0,).$

$a.$ Find the unit vectors that give the direction $of$ steepest ascent and steepest descent $atP.$

$b.$ Find a vector that points $in$ a direction $ofno$ change $in$ the function $atP.$

$a.$ What $is$ the unit vector $in$ the direction $of$ steepest ascent $atP?$

$(Type$ exact answers, using radicals $as$ needed.$)$

What $is$ the unit vector $in$ the direction $of$ steepest descent $atP?$

$(Type$ exact answers, using radicals $as$ needed.$)$

$b.$ Which $of$ the following vectors $isin$ a direction $ofno$ change $of$ the function $atP?$

$A.($:$-14,-8$:$)$

$B.($:$8,-14$:$)$

$C.($:$14,8$:$)$

$D.($:$8,14$:$)$