b We are asked to find the sum of the following arithmetic sequence.
1, 2, 3, 4, ..., 1000
For this sequence, the first sequence is a_1= 1, the common difference is d=2-1= 1, and the last term is a_n= 1000. First, let's find the number of terms in the given sequence. We will use the formula for the explicit rule of arithmetic sequences.
a_n= a_1+(n-1) d
Now, we will substitute values into the formula and solve if for n.
a_n= a_1+(n-1) d
1000= 1+(n-1) 1
n=1000
Next, we will calculate the sum of the given sequence.
1+2+3+...+1000
To do this, we will use the formula for finding the sum of an arithmetic series for n=1000.
S_()darkorangen=n(a_1+a_()darkorangen)/2
⇓
S_()darkorange1000=1000(a_1+a_()darkorange1000)/2
Finally, we will substitute 1 for a_1 and 1000 for a_(1000), and then find the sum.
S_(1000)=1000( a_1+ a_(1000))/2
S_(1000)=1000( 1+ 1000)/2
S_(1000)=1000(1001)/2
S_(1000)=1 001 000/2
S_(1000)=500 500
This tells us that the sum of the given arithmetic sequence is 500 500.