What would happen when we change w1,w2, and P12

Suppose we hold 2 stocks: E(R_1)=0.15, E(R_2)=0.30, sigma_1^2=0.10, sigma_2^2=0.25. Thus, sigma_1=0.316, sigma_2=0.50. Let w_1 be the fraction of our wealth placed in stock 1 and w_2=1-w_1 the fraction in stock 2. E(R_P) = w_1E(R_1)+w_2E(R_2) = 0.15w_1 + 0.30w_2 sigma_P^2=w_1^2 sigma_1^2+w_2^2 sigma_2^2+2w_1w_2p_12 sigma_1 sigma_2 =w_1^2(0.10)+w_2^2(0.25)+2w_1w_2p_12(0.316)(0.50) What would happen when we change w_1, w_2, and p_12