Question textSuppose [math: f(x,y)=y2−xy+3x+1]. (a) What is the maximum rate of increase of [math: f] at the point [math: (1,1)]? [input] Your last answer was interpreted as follows: 2.23606797749979This answer is invalid. Your answer contains floating point numbers, that are not allowed here. You need to type in numbers as fractions. For example, you should type 1/3 not 0.3333, which is after all only an approximation to one third. (b) What is the directional derivative of [math: f] at the point [math: (1,1)] in the direction of the vector [math: (−1,−1)]? [input] Your last answer was interpreted as follows: -2.1213203435596424This answer is invalid. Your answer contains floating point numbers, that are not allowed here. You need to type in numbers as fractions. For example, you should type 1/3 not 0.3333, which is after all only an approximation to one third. (c) The tangent plane to the graph of [math: f] at [math: (1,1,f(1,1))] is of the form [math: ax+by+cz=d], where [math: [a,b,c,d]=] [table] | | | | | [/table] Your last answer was interpreted as follows: [math: [21−1−1]] Check Question 2多项填空题