Given equation is 2x2+(a+3)x+8=0 Here, A=2,B=a+3 and C=8 If roots are equal, then B2−4AC=0 ⇒‌‌(a+3)2−4×2×8=0 ⇒‌‌a2+6a+9−64=0 ⇒‌‌a2+6a−55=0 ⇒‌‌a2+11a−5a−55=0 ⇒‌‌(a+11)(a−5)=0 ∴‌‌a=−11,5∴‌‌a=−11,5