Question

If a²+b²+c²=29 and a+b+c=9; find ab+bc+ca​

Answer 1

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□□Solution□□

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Since (a+b+c)²=a²+b²+c²+2 (ab+bc+ca)

Therefore (9)²=29+2 (ab+bc+ca)

➡81-29=2(ab+bc+ca)

Therefore, ac+bc+ca=52/2= 26

Hope it helps you...

Answer 2

Answer:

1. a+b+c whole square = a^2+b^2+c^2+2(ab+bc+ca)
2. 9 whole square =29+2×(ab+bc+ca)
3. 81=29+2(ab+bc+ca)
4. 81-29/2=(ab+bc+ca)
5. 26=(ab+bc+ca)