Answer:
9/2
Step-by-step explanation:
Answer:
This means c=100. The factored form is 
.
Step-by-step explanation:
A perfect square is a trinomial that factors into the form 
. To find the value of C to finish the perfect square divide 20 by 2 and square it.
20/2 = 10
10*10=100
This means c=100. The factored form is .
To factor, you split the equation so the factors multiply to get the whole equation.
(x-2)(x+2)
Then, interpret the factors.
The zeros can be found at (2,0) and (-2,0).
x=2, x=-2
Answer:
ai) 73000 gal/yr
aii) $730 per year
b) 1000 days
Step-by-step explanation:
ai) The water usage per day is ...
(4 showers/day)(10 min/shower)(5 gal/min) = 200 gal/day
Then the usage per year is ...
(200 gal/day)(365 days/yr) = 73,000 gal/yr
__
aii) The cost of electricity is the cost of heating half the water usage, so is ...
(0.20 kWh/gal)(1/2)(73,000 gal/yr)($0.10/kWh) = $730/yr
__
b) The current daily cost of electricity for heating water is ...
($730/yr)/(365 days/yr) = $2/day
If the cost is cut in half, it will be $1 per day. That means the savings is $1 per day, so it will take 1000 days to recover the $1000 initial cost. (Effectively, the average cost for the first 1000 days is the same as if the water heater had not been replaced.)
