Question

Which expression equals zero if x = 3

and y = -3?
(1) x² - y²
(2) x² + y²
(3) xy
(4) x-y

Answer 1

The expression that equals zero when x = 3 and y = -3 is x² - y².

Therefore, the correct answer is: option (1) x² - y².

Step-by-step explanation:

To find the correct expression, we substitute the values of x and y into each expression and simplify.

x² - y² = (3)² - (-3)²

= 9 - 9

= 0.

So, expression (1) equals zero.

x² + y² = (3)² + (-3)²

= 9 + 9

= 18.

This expression does not equal zero.

xy = 3 * (-3) = -9.

This expression does not equal zero.

x - y = 3 - (-3)

= 3 + 3

= 6.

This expression does not equal zero.

Therefore, the expression that equals zero when x = 3 and y = -3 is (1) x² - y².