Question

Which term of the sequence -1, 3, 7, 11, ....., is 95 ? Also find 15th term from the end.​

Answer 1

Answer:

25th term,

Step-by-step explanation:

First term is -1

difference is 4

now by formula

95=-1+(n-1)4

96=(n-1)4

24=n-1

n=25

so 25th term is 95

Answer 2

Answer :

$\Large\bold{\underline{\sf{\pink{Given:}}}}$

• A.P. = -1, 3, 7, 11, ...

$\Large\bold{\underline{\sf{\pink{To\:Find:}}}}$

• Which term is 95 and 15th term of A.P.

$\Large\bold{\underline{\sf{\pink{Sølution:}}}}$

Here , a = -1 , d = 3-(-1) = 3+1 = 4

☯ FORMULA USED :

$\bold{\boxed{\boxed{\sf{\red{a_n\:=\:a\:+\:(n\:-\:1)d}}}}}$

Now , here ${\sf{\red{a_n}}}$ = 95

• $\sf 95\:=\:-1\:+\:(n\:-\:1)4$

• $\sf 95\:=\:-1\:+\:4n\:-4$

• $\sf 95\:=\:4n\:-\:5$

• $\sf 95\:+\:5\:=\:4n$

• $\sf 100\:=\:4n$

• $\sf n\:=\: \dfrac{100}{4}$

$\large\bold{\underline{\underline{\mathtt{\pink{n\:=\:25}}}}}$

☯ For second part of question , last term is not given .

But the formula used will be :

$\bold{\boxed{\boxed{\sf{\red{{n}^{th}\:term\:from\:last\:=\:l\:-\:(n\:-\:1)d}}}}}$

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