If a2 + b2 + c2 = 281 and ab + bc + ca =4, then a + b + c is	Answers:
A) 16	B) 18	C) 22	D) 17	E) 20
by formula ,   (a + b + c)^2= a^2 + b^2 + c^2 + 2(ab + bc + ca),   since, a^2 + b^2 + c^2 = 281 and ab + bc + ca = 4,   (a + b + c)^2 = 281 + 2(4)   = 289   = 17^2   therefore: a + b + c = 17   ANSWER:17
<result>D</result>
If a2 + b2 + c2 = 281 and ab + bc + ca =4, then a + b + c is