Question

Please solve the question fast.
.
Question-
Find the 10th term from the last term of the AP :4.9.14, ...,254.
Answer-209​

Answer 1

Answer:

Step-by-step explanation:

Ap is 4,9,14,.....254

By reversing the AP

Ap is 254,249,244,......9,4

So, a=254,d=-5,l=4

So, a10=a+(10-1)d

=254+9×-5

=254-45

=209

Thank u

Answer 2

Solution :

$\underline{\bf{Given\::}}}$

• First term, (a) = 4
• Common difference, (d) = 5
• Last term, (l) = 254

Now;

$\bigstar$ Using formula of an A.P;

$\boxed{\bf{a_{n} = a+(n-1)d}}}}$

$\longrightarrow\sf{254=4 + (n-1)5}\\\\\longrightarrow\sf{254 = 4 + 5n - 5}\\\\\longrightarrow\sf{254 = 5n - 1}\\\\\longrightarrow\sf{5n=254 + 1}\\\\\longrightarrow\sf{5n=255}\\\\\longrightarrow\sf{n=\cancel{255/5}}\\\\\longrightarrow\bf{n=51}$

A/q

$\longrightarrow\sf{a(n-10) + 1} \\\\\longrightarrow\sf{a(51-10 )+ 1}\\\\\longrightarrow\sf{a(41 ) +1}\\\\\longrightarrow\sf{a_{42} }$

$\longrightarrow\sf{a_{42} = 4 + (42-1)\times 5}\\\\\longrightarrow\sf{a_{42} = 4+ 41\times 5} \\\\\longrightarrow\sf{ a_{42} = 4+ 205}\\\\\longrightarrow\bf{a_{42} = 209 }$