8. The area of the parallelogram whose adjacent sides formed by the vectors usi+i-k and v= 2i-j+3k is a) √32 b) 12 c) √38 d) √38 2 e) None of the above. 9. The direction in which the function f(x,y) = x² + xy + y² increases most rapidly at the point P(-1, 1) is a) < > b) < 1/2, 2/2² > <唔唔> d) < = 1/2 - 1/²2 > d) <= 1/2, 1/2 > e) None of the above. aw Let w = √² + s², r = y + x cost and s= x + y sint. Then at -rxsin + sy cost √r²+5² rxsint-s y cost √r²+5² rxsint+s y cost √r²+ s² sxsint-ry cos t d) √r²+ s² e) None of the above. 10. a) b) c) is