Answer:
hello :
note : 1+2+3+.......+n = n(n+1)/2
Step-by-step explanation:
in this exercice : n = 45
1+2+3+...+45 = 45×46/2 = 1035
Answer: 1035
[tex]\sum^{45}_{1}i\\\\\text{The sum of an arithmetic sequence is:}\ \dfrac{a_1+a_n}{2}\cdot n\\\\= \dfrac{1+45}{2}\cdot 45\\\\\\=\dfrac{46}{2}\cdot 45\\\\\\=23\cdot 45\\\\=1035[/tex]
