Answer:
2 days
Step-by-step explanation:
The first day Jerry did 14 sit-ups, so the first term of arithmetic sequence is
[tex]a_1=14[/tex]
Everyday after that he did 4 more sit-ups than he had done the previous day, then the common differentce is
[tex]d=4[/tex]
Today Jerry did 22 sit-ups, hence
[tex]a_n=22[/tex]
Use formula for nth term of arithmetic sequence:
[tex]a_n=a_1+(n-1)d[/tex]
So
[tex]22=14+(n-1)\cdot 4\\ \\22=14+4n-4\\ \\22=4n+10\\ \\4n=22-10\\ \\4n=12\\ \\n=3[/tex]
If not counting the first day, Jerry needs 2 days
