(45 points) Let l1,l2:RR3be two lines in space given by the parameterizationsl1(t):(:2,13,7:)+t(:-1,5,0:),l2(s):(:1,6,1:)+s(:2,-4,3:)(a) Show that the two lines intersect at a point.(b) Find an equation for the plane that contains the two lines l1 and l2.(c) Find a vector projection of the vector u=(:4,2,1:)on the normal direction to the plane. (15pts) Find the tangent line to the curve r(t)=(:t3+1,5-t4,t2-2:)at the point wheret=1.(40 points) A function f:R2Ris given byf(x,y)=2-y2.(a) Make a contour plot by plotting the level curves corresponding to the values {-2,-1,0,1,2}.(b) What kind of surface is the graph offinR3? You can answer this by naming thesurface, describing itin words andor sketching itinR3.