Question

The common difference of an A.P. in which $a_{25}-a_{12}=-52$ is:

• A. 4
• B. $-4$
• C. $-3$
• D. 3

Answer 1

The correct option is B $-4$

Let $a_1=a$

$\therefore a_{25}=a_1+24d$ ...eq ( 1 )

$\therefore a_{12}=a_1+11d$ ...eq ( 2 )

eq ( 1 ) - eq ( 2 )

$a_1+24d-a_1-11d=-52$

$13d=-52$

$\therefore d=-4$