OG详解-OG4 数学2 Q4

Choice A is correct. The second equation in the given system defines the value of x as 5y. Substituting 5y for x into the first equation yields 5y + y =18 or 6y =18. Dividing each side of this equation by 6 yields y = 3. Substituting 3 for y in the second equation yields 5(3)= x or x =15. Therefore, the solution (x, y ) to the given system of equations is (15, 3).
Choice B is incorrect. Substituting 16 for x and 2 for y in the second equation yields 5(2)=16, which is not true. Therefore, (16, 2) is not a solution to the given system of equations. Choice C is incorrect. Substituting 17 for x and 1 for y
in the second equation yields 5(1)=17, which is not true. Therefore, (17, 1) is not a solution to the given system of equations. Choice D is incorrect. Substituting 18 for x and 0 for y in the second equation yields 5(0)=18, which is not true. Therefore, (18, 0) is not a solution to the given system of equations.