Question

if a+b+c=7 and ab+bc+ca=20 then find the value of a square + b square + c square​

Answer 1

Step-by-step explanation:

(a+b+c)2= a2+b2+c2+2(ab+bc+ca)

72 = a2+b2+c2+ 2×20

49 = a2+b2+c2 + 40

49 - 40 = a2+b2+c2

.·. 9 = a2+b2+c2

Ans : 9

Answer 2

Answer:

step by step explanation :

(a+b+c)² = a²+b²+c²+2ab+2bc+2ca

a²+b²+c² = (a+b+c)²-2ab-2bc-2ca

a²+b²+c²v = (7)² -2 (ab+bc+ca) a²+b²+c²

=(7)² -2(20) a²+b²+c²

= 49 -40

= a²+b²+c² = 9

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