Let the four terms in an AP are (a−3d),(a−d),(a+d) and (a+3d) Given, a1+a4=10 ⇒‌‌(a−3d)+(a+3d)=10 ⇒‌‌2a=10⇒a=5 and a2⋅a3=24 ⇒‌‌(a−d)(a+d)=24 ⇒‌‌(a2−d2)=24 ⇒‌‌25−d2=24 ⇒‌‌d2=1 ∴‌‌d=±1 When (d=1), then terms are : 2,4,6,8 and when (d=−1), then terms are : 8,6,4,2 .