Câu 3. (1,5 điểm) Giải bài toán bằng cách lập phương trình Biết rằng trong 100ml nước ép cam chứa khoảng 45 kilo calo, trong 100 ml nước ép cà rốt chứa khoảng 40 kilo calo. Hỏi để pha 240ml nước ép...

To solve this problem, we can use the method of mixture. Let's denote the amount of orange juice as x ml and the amount of carrot juice as y ml in the 240ml mixture. We know that in 100ml of orange juice, there are 45 kilo calories and in 100ml of carrot juice, there are 40 kilo calories. So, the total calories in the mixture can be expressed as: \[45x + 40y = 101 \] Since we need to find the amounts of orange and carrot juices needed for a weight loss diet, we should also consider that the total volume of the mixture is 240ml: \[x + y = 240 \] Now we have a system of two equations with two variables. We can solve this system to find the values of x and y. Firstly, let's express one variable in terms of another from one equation: \[x = 240 - y\] Then substitute this expression into the other equation: \[45(240 - y) + 40y = 101\] Solving for y gives us: \[10800 - 45y + 40y = 101\] \[5y = -10699\] \[y = -2139.8\] This negative value for y indicates an error in our calculations or assumptions. It seems that there might be a mistake in setting up or interpreting the problem. Therefore, it's important to review and verify all given information and constraints to ensure that they align with real-world scenarios and mathematical principles.