Use a diagram to explain the following: In the case of perfect substitutes, if the ratio of

Question:

Use a diagram to explain the following: In the case of perfect substitutes, if the ratio of input prices equals the MRTS, will a unique solution to the firm's cost-minimization problem exist? In the case of perfect substitutes, if the ratio of input prices does not equal the MRTS, where will we find the solution to the firm's cost minimization problem graphically?