Step 1 :Let's denote the amount of the first alloy (49% copper) as x and the amount of the second alloy (62% copper) as y.
Step 2 :We know that the total amount of the two alloys is 51 pounds, so we have the equation \(x + y = 51\).
Step 3 :We also know that the total amount of copper in the two alloys is 56% of 51 pounds, so we have the equation \(0.49x + 0.62y = 0.56 * 51\).
Step 4 :We can solve this system of equations to find the values of x and y.
Step 5 :Final Answer: The metallurgist must use \(\boxed{x}\) pounds of the first alloy and \(\boxed{y}\) pounds of the second alloy to make 51 pounds of a third alloy containing 56% copper.