a + b + c = 9, a2 + b2 + c2 = 29 হলে ab + bc + ca = কত?
সমাধান
সঠিক উত্তর: Option D
a²+b²+c²=(a+b+c)²-2(ab+bc+ca)
=> 29 =(9)²-2(ab+bc+ca)
=> 2(ab+bc+ca) =81-29
∴ab+bc+ca=26
=> 29 =(9)²-2(ab+bc+ca)
=> 2(ab+bc+ca) =81-29
∴ab+bc+ca=26
