Step-by-step explanation:
(n + 7)² – n²
n² + 14n + 49 – n²
14n + 49
7 (2n + 7)
7 is a factor, so for any natural n, (n + 7)² – n² is a multiple of 7.
Tha last one PR=XY is not true.
It should be PR=XZ.
You cannot have an answer to this because it is not an equation
Answer:
a) $0.97
b) $0.16
c) $24.30
Step-by-step explanation:
$0.09 per kilowatt hour = $0.09/kWh
6h/day 30 days = 180h
a) 60W*180h = 10800 Wh = 10.8kWh
10.8kWh * $0.09/kWh = $0.97
b) P = V*I
V = 120V
I = 80mA = 80/1000 = 0.08A
P = 120*0.08 = 9.6W
9.6W*180h = 1728 Wh = 1.728kWh
1.728kWh * $0.09/kWh = $0.16
c) 1500W*180h = 270000 Wh = 270kWh
270kWh * $0.09/kWh = $24.30
Answer: x^3 - 1 = (x - 1)(x^2 + x + 1)
Explanation:
This is a type of factorizing called the sum or difference of 2 cubes:
a^3 - b^3 = (a - b)(a^2 + ab + b^2)
The sum of the cubes is factored as:
a^3 + b^3 = (a + b)(a^2 - ab + b^2)
In this case, we have: x^3 - 1 so follow the rule above.
x^3 - 1 = (x - 1)(x^2 + x + 1)