For these kinds of expressions use FOIL (first, outside, inside, last).

-2x • 9x = -18x^2
-2x • -3y = 6xy
8y • 9x = 72 xy
8y • -3y = -24y^2

Now combine them all:

-18x^2 + 78xy - 24y^2

6 0

3 years ago

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The observation deck of the willis tower in Chicago Illinois is 1353 feet above the ground elevators lift visitors to that level

Paul [167]

Answer: The the speed of elevators is 22.55.

Explanation:

It is given that observation deck of the willis tower in Chicago Illinois is 1353 feet above the ground elevators lift visitors to that level in 60 seconds.

The speed is the change in distance with respect to time.

$\text{Average Speed}=\frac{\text{Total Distance}}{\text{Total Time}}$

From the given information the total distance is 1353 and the total time is 60 seconds. So by the above formula we get,

$\text{Average Speed}=\frac{1353}{60}$

$\text{Average Speed}=22.55$

Therefore, the speed of elevators is 22.55.

8 0

3 years ago