Question

Evaluate 3+11t -9u3+11t−9u3, plus, 11, t, minus, 9, u when t=9t=9t, equals, 9 and u=11u=11u, equals, 11.

Answer 1

3

Explanation:

Let's substitute t = 9 and u = 11 into the expression.

3+11t−9u

=3+11(9)−9(11)

=3+99-99=3+99−99

=3

Answer 2

3

Explanation:

Fill in the numbers and do the arithmetic:

3+11t -9u = 3 + 11(9) -9(11) = 3

_____

Your understanding of the commutative property of multiplication lets you observe that 11·9 = 9·11. You also know that adding opposites results in zero, so 11·9 - 9·11 = 0

Of course, 3 + 0 = 3.

In other words, you don't actually have to work it out as ...

3 + 11(9) -9(11)

= 3 + 99 - 99

= 102 -99

= 3