Question

if a square+b square +c square=30 and a+b+c=10then find value if ab+bc+ca
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Answer 1

Answer:

ab+bc+ca=35

Step by step explanation:

(a+b+c)²=a²+b²+c²+2ab+2bc+2ca

(10)²=30+2(ab+bc+ca)

100=30+2(ab+bc+ca)

100-30=2(ab+bc+ca)

70=2(ab+bc+ca)

35=ab+bc+ca

Answer 2

Answer: 35

Given: a²+b²+c² = 30 and a+b+c = 10

To find: ab+bc+ca

Explanation:

We know that,

a²+b²+c² can also be written as (a+b+c)²

Expanding (a+b+c)² we get,

(a+b+c)²= a²+b²+c²+2ab+2bc+2ca

Substituting the values, we get:

(10)²=30+2(ab+bc+ca)

100=30+2(ab+bc+ca)

100-30=2(ab+bc+ca)

70=2(ab+bc+ca)

35=ab+bc+ca

Therefore, the value of ab+bc+ca is 35