I just want to check to make sure I am correct --
my equation is y = -x^2 + 90x - 800
If x = 100, -x^2 would be 10,000, not -10,000? Because -100 x -100 is 10,000, not -10,000 --- my calculator keeps giving me a negative number.
So my overall number is 18,200
NO
-x^2 is the same as
-1 * x^2
=-1 * 10,000
= -10,000
In other words your calculator won the argument this time :)
To find the value of y when x = 100 in the equation y = -x^2 + 90x - 800, let's calculate step by step:
1. Calculate -x^2:
-x^2 = -(100)^2 = -10,000
2. Calculate 90x:
90x = 90 * 100 = 9,000
3. Now, substitute the values into the equation to find y:
y = -x^2 + 90x - 800
= -10,000 + 9,000 - 800
= -10,800 + 9,000
= -1,800
Therefore, when x = 100, the value of y in the equation y = -x^2 + 90x - 800 is indeed -1,800, not 18,200. It appears there was an error in your calculation or understanding.