It is asking you to find the sum of k^2 - 1 from k=1 to k=4. Since that is only 4 numbers, calculating the sum by hand wouldn’t be that bad.
(1^2 - 1) + (2^2 - 1) + (3^2 - 1) + (4^2 - 1) = 26
The easier way to find the sum is to use a few simple formulas.
When we have a term that is just a constant c, the formula is c*n.
When we have a variable k, the formula is k*n*(n+1)/2.
When we have a squared variable, the formula is k*n*(n+1)*(2n+1)/6.
In this case, we have a squared variable k^2 and a constant of -1.
So plug in n=4 to the formulas:
4*5*9/6 - 1*4 = 26
The answer is 26
Step-by-step explanation:
.......................................................... (2×3)+(6×3)
Answer:
-2/3
Step-by-step explanation:
Where 2 lines are perpendicular, the slope of one = - 1 / slope of the other.
Thus the slope of the red line is - 1 / 3/2
= -2/3
Answer:
-1
Step-by-step explanation:
Twice a number of 4 equals 8
4×2=8
less than 9 of the quotient (answer) of twice a number of 4, is -1
8-9= -1
