Question

: Find the value of ab + bc + ca when a + b + c = 13 and a 2 + b 2 + c 2 = 69

Answer 1

Answer:

50

Step-by-step explanation:

Given,

a²+b²+c²=69

a+b+c=13

(a+b+c)² = a² + b² + c² + 2(ab+bc+ca)

(13)² = 69 + 2(ab+bc+ca)

169 = 69 + 2(ab+bc+ca)

169-69 = 2(ab+bc+ca)

100 = 2(ab+bc+ca)

ab+bc+ca = 100/2

ab+bc+ca = 50

Answer 2

ab+bc+ca = 50
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