Answer: 
Step-by-step explanation:
Let be "x" the height inches (in the model) of a 84 foot building.
According to the information provided in the exercise, we know that the height of a two-story building is 21 feet and in the scale model its height is 3 inches.
Knowing this, we can set up the following proportion:

The final step is to solve for "x" in order to calculate its value. We get that this is:

Therefore, an 84 foot building will be 12 inches tall in the model.
Answer:
what is the quastion
Step-by-step explanation:
plz
Answer:
y-intercept: 10
concavity: function opens up
min/max: min
Step-by-step explanation:
1.) The definition of a y-intercept is what the resulting value of a function is when x is equal to 0.
Therefore, if the function's equation is given, to find y-intercept simply plug in 0 for the x-values:

y intercept ( f(0) )= 10
2.) In order to find concavity (whether a function opens up or down) of a quadratic function, you can simply find the sign associated with the x^2 value. Since 2x^2 is positive, the concavity is positive. This is basically possible, since it is identifying any reflections affecting the y-values / horizontal reflections.
3.) In order to find whether a quadratic function has a maximum or minimum, you can use the concavity of the function. The idea is that if the function opens downwards, the vertex would be at the very top, resulting in a maximum. If a function was open upwards, the vertex would be at the very bottom, meaning there is a minimum. Like the concavity, if the value associated with x^2 is positive, there is a minimum. If it is negative, there is a maximum. Since 2x^2 is positive, the function has a minimum.
A, B, D
A: because there are two colour types in a deck of cards, so it’s 1/2 probability of getting a black one.
B: because there a four suits in a deck of cards, so the probability of getting a diamond is 1/4
D: because when calculating compound events we multiply the two probabilities,
so 1/2 x 1/4 = 1/8