Question

If a + b + c = 9 and ab + bc + ca = 15 find a2 + b2 + c​

Answer 1

Answer:

Using (a+b+c)²=a²+b²+c²+2(ab+bc+ca)

a²+b²+c²=(a+b+c)²-2(ab+bc+ca)

a²+b²+c²= 9² -2(15)

a²+b²+c²=81-30=51

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