Question

Please answer THE 4th question here , elaborate

Answer 1

$\huge{\pink{\underline{\ulcorner{\star\: Solution\: \star}\urcorner}}}$

$\red{\underline{\bold{Given}}}$

$a = 1\\ l= 11 \\ S_n = 36 \\n(number\:of\: terms ) = ?$

$\red{\underline{\bold{Solution}}}$

$S_n = \frac{n}{2}(a+l) \\ 36 =\frac{n}{2}(1+11)\\ 36 \times 2 = n(12) \\ 12n = 72\\ n=\frac{72}{12} \\ n = 6$

$\red{\underline{Answer}}$

$\green{\bold{\boxed{ n\: = \: 6}}}$

Answer 2

Hello!

$\star \: \sf a = 1 \\ \star \: \sf l = 11 \\ \star \: \sf S_{n} = 36$

Then,

$\sf S_{n} = \dfrac{\sf n}{2}(\sf a + l) \\ \\ \implies 36 = \dfrac{\sf n}{2}(1 + 11) \\ \\ \implies 36 = \dfrac{\sf n}{2} \times 12 \\ \\ \implies \sf 6n = 36 \\ \\ \implies \sf n = \dfrac{36}{6} \implies \boxed{\red{\bf{n = 6}}}$

Cheers!