There are two ways to work this out: normal variables or using "imaginary" numbers.
Normal variables:
![(7+2i)(3-i)\\(7*3)+[7*(-i)]+(3*2i)+[2i*(-i)]\\21-7i+6i-2i^{2}\\\\21-i-2i^{2}](https://tex.z-dn.net/?f=%20%287%2B2i%29%283-i%29%5C%5C%287%2A3%29%2B%5B7%2A%28-i%29%5D%2B%283%2A2i%29%2B%5B2i%2A%28-i%29%5D%5C%5C21-7i%2B6i-2i%5E%7B2%7D%5C%5C%5C%5C21-i-2i%5E%7B2%7D)
Imaginary numbers:
Using the result from earlier:
Now since
, then the expression becomes:
The volume of a cone is = pi r^2 h/3
and the volume of the pyramid is = V= l w h/3
Hope this helps!
can I get a brainleist
Subtract all the operating expenses from the amount he spent total and get what's left over is $491. That's what he spent on gas. Divide the number of miles he drove by the amount he spent on the gas to find out what the average cost of the gas was per mile. 491/7270 = .06753. But that is expressed in dollars and we need it in cents. Multiply that decimal by 100 to get 6.75 cents, choice A from above.
