Multivariable calculus generalises the single-variable toolkit. Two operations matter most for quant work: partial derivatives (sensitivities, Greeks) and iterated integrals (expectations over joint distributions).
For f(x,y)=x2y3:
(a) Compute the mixed partial derivative ∂x∂y∂2f.
(b) Evaluate the double integral ∬Rf(x,y)dA over the rectangle R=[0,1]×[0,2].