Question

Find The no. of terms in the AP whose first term is 7, last term is 43 and sum is 400

Answer 1

Solution :

$\bigstar$Firstly, we know that formula of the last term of an A.P;

$\boxed{\bf{S_n=\frac{n}{2} \bigg[a+l\bigg]}}}}$

• a is the first term.
• l is the last term.
• n is the term of number.

A/q

$\longrightarrow\sf{400=\dfrac{n}{2} \bigg[7+43\bigg]}\\\\\\\longrightarrow\sf{800=n(50)}\\\\\longrightarrow\sf{800=50n}\\\\\longrightarrow\sf{n=\cancel{800/50}}\\\\\longrightarrow\bf{n=16}$

Thus;

The number of term will be 16 .

Answer 2

Step-by-step explanation:

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