A student read common difference of an A. P. as -2 instead of 2 and got the sum of first 5 terms as -5. Actual sum of first five terms is

Question

A student read common difference of an A. P. as -2 instead of 2 and got the sum of first 5 terms as -5. Actual sum of first five terms is (A) 25 (B) -25 (C) -35 (D) 35

Tardigrade Admin · Accepted Answer

(5/2) 2 a+4(-2) =-5 ⇒ 2 a=6 ∴ Actual sum =(5/2) 6+4(2) =35

Q. A student read common difference of an A. P. as $- 2$ instead of $2$ and got the sum of first $5$ terms as $- 5$ . Actual sum of first five terms is

25

-25

-35

35

$\frac{5}{2} {2 a + 4 (- 2)} = - 5 \Rightarrow 2 a = 6$
$∴$ Actual sum $= \frac{5}{2} {6 + 4 (2)} = 35$

Q. A student read common difference of an A. P. as −2 instead of 2 and got the sum of first 5 terms as −5. Actual sum of first five terms is

25

-25

-35

35

25​{2a+4(−2)}=−5⇒2a=6 ∴ Actual sum =25​{6+4(2)}=35

Q. A student read common difference of an A. P. as $- 2$ instead of $2$ and got the sum of first $5$ terms as $- 5$ . Actual sum of first five terms is

$\frac{5}{2} {2 a + 4 (- 2)} = - 5 \Rightarrow 2 a = 6$
$∴$ Actual sum $= \frac{5}{2} {6 + 4 (2)} = 35$