We can find the answer by solving the two equations simultaneously.

equation 1: y = -0.4x^2 +3xequation 2: x + y = 10
We need to write equation to with y as the subject:equation 2: y = 10 - x

equation 1 = equation 2:
10 - x = -0.4x^2 + 3x0.4x^2 - 4x + 10 = 02x^2 - 20 + 50 = 0(2x - 10)(x - 5) = 0x = -10/2 or x = 5

But x >= 0 (the question says it's a height above the water), so x = 5

Substituting x = 5 into one of the equations:
y = 10 - x
y = 10 - 5
y = 5

So the answer is C

7 0

4 years ago

2. A faucet for a 30-gallon bathtub fills at a rate of 3 gallons per minute.

denis-greek [22]

Answer:

Step-by-step explanation:

Knowing that it is a 30-gallon bathtub.

And it fills at a rate of 3 gallons per minute.

But also drains 1.5 gallons per minute.

So this is for the first minute.

3 - 1.5 = 1.5

So there will be 1.5 gallons of water in the tub after the first minute.

Now do,

30 ÷ 1.5 = 20

It will take 20 full minutes for the bathtub to fill up.

6 0

3 years ago