`a_4=16 `
`a_10=46`
To determine the first five terms of this arithmetic sequence, consider its nth term formula which is:
`a_n=a_1+(n-1)d`
To apply this, plug-in the given nth terms.
Plugging in a_4=16, the formula becomes:
`16=a_1 + (4-1)d`
`16=a_1+3d ` (Let this be EQ1.)
Also, substituting a_10=46, the formula becomes:
`46=a_1+(10-1)d`
`46=a_1+9d ` (Let this be EQ2.)
Then, use these two equations to solve for the...
`a_4=16 `
`a_10=46`
To determine the first five terms of this arithmetic sequence, consider its nth term formula which is:
`a_n=a_1+(n-1)d`
To apply this, plug-in the given nth terms.
Plugging in a_4=16, the formula becomes:
`16=a_1 + (4-1)d`
`16=a_1+3d ` (Let this be EQ1.)
Also, substituting a_10=46, the formula becomes:
`46=a_1+(10-1)d`
`46=a_1+9d ` (Let this be EQ2.)
Then, use these two equations to solve for the values of a_1 and d. To do so, isolate a_1 in the first equation.
`16=a_1+3d`
`16-3d=a_1`
Plug-in this to the second equation.
`46=a_1+9d`
`46=16-3d+9d`
`46=16+6d`
`30=6d`
`5=d`
Then, solve for a_1. To do so, plug-in d=5 to the first equation.
`16=a_1 + 3d`
`16=a_1+3(5)`
`16=a_1+15`
`1=a_1`
Then, plug-in these two values a_1=1 and d=5 to the formula of nth terms of arithmetic sequence.
`a_n=a_1+(n-1)d`
`a_n=1+(n-1)(5)`
`a_n=1+5n-5`
`a_n=5n-4`
Now that the formula of a_n is known, use this to solve for the values of a_2, a_3 and a_5. (Take note that the values of a_1 and a_4 are already known.)
1st term: `a_1=1`
2nd term: `a_2=5(2)-4=6`
3rd term: `a_3=5(3)-4=11`
4th term: `a_4=16`
5th term: `a_5=5(5)-4=21`
Therefore, the first five terms of the arithmetic sequence are {1, 6, 11, 16, 21,...}.
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