m(a + b)(a - b)× m(b - c)(b + c)× m(c + a)(c - a)= ?
সঠিক উত্তর
0
১ + ৫ + ৯ + ........... +৮১ = ?
m(a + b)(a - b) × m(b - c)(b + c) × m(c + a)(c - a)
= m(a2 - b2) × m(b2 - c2) × m(c2 - a2)
= ma2 - b2 + b2 - c2 + c2 - a2
= m0
= 1