Practicing Success
If (a + b + c) = 6 a2 + b2 + c2 = 32 a3 + b3 + c3 = 189 find the value of abc + 3 |
6 8 0 6 |
6 |
(a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca) 36 = a2 + b2 + c2 + 2(ab + bc + ca) 36 = 32 + 2(ab + bc + ca) ab + bc + ca = 2 Now → a3 + b3 + c3 – 3abc = (a + b + c)(a2 + b2 + c2 - ab - bc - ca) 189 – 3abc = 6(32 – 2) abc = 3 abc + 3 = 6 |