Suppose the firm's cost minimization problem is: min L,K wL + rK subject to Q = 4KL and is in the long run with adjustable capital and labor.

I need to solve for the firm's optimal amount of labor (L ) and capital (K ) needed to produce any level of output (Q) given the cost of labor (w) and cost of capital (r). But my professor doesn't use the lagrange multiplier, which is what most examples online uses.