[email protected] wrote:Need to understand the question being asked here, before understanding the process to solve!
The cost of 1 hour's worth of electricity depends on how many kilowatts of electricity were used.
x = the number kilowatts of electricity used
The cost of 1 hour of electricity = 2 + 5/√(3-x)
So, for example, if we use 2 kilowatts, x =
2, then . . .
the cost of 1 hour of electricity = 2 + 5/√(3-
2)
= 2 + 5/√1
= 7 (dollars)
The question tells us that the cost of 1 hour of electricity =
$9.00
So, we can write:
9 = 2 + 5/√(3-x)
[we must solve for x]
Subtract 2 from both sides: 7 = 5/√(3-x)
Multiply both sides by √(3-x) to get: 7√(3-x) = 5
Divide by 7 to get: √(3-x) = 5/7
Square both sides to get: 3-x = 25/49
Solve for x: x = 3 - 25/49
Since 25/49 ≈ 0.5, we can see that x ≈ 3 - 0.5 ≈
2.5
Cheers,
Brent
