Answer:
28
Explanation:
To evaluate the expression '2x - 5xy + 7' when x = 3 and y = -1, substitute these values into the expression:
⇒ 2x - 5xy + 7
⇒ 2(3) - 5(3)(-1) + 7
Now, perform the operations:
⇒ 2(3) - 5(3)(-1) + 7
⇒ 6 + 15 + 7
∴ = 28
So, the expression 2x - 5xy + 7 evaluates to 28 when x = 3 and y = -1.