Question

If a+b+c=9 and
ab+bc+ca=26 find a^2+b^2+c^2

Answer 1

Hi dear friend!!

here is the your Answer
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$a + b + c = 9 \\ ab + bc + ca = 26 \\ \\ now \\ \\ (a + b + c {)}^{2} = {a }^{2} + {b}^{2} + {c}^{2} + 2ab + 2bc + 2ca \\ now \: putting \: the \: value \\ \\ {9}^{2} = {a}^{2} + {b}^{2} + {c}^{2} + 2 \times 26 \\ {a}^{2} + {b}^{2} + {c}^{2} = 81 - 52 \\ {a}^{2} + {b }^{2} + {c}^{2} = 29 \: ans \\ \\ hope \: its \: helpful$

Answer 2

In this identity will use that is, (a+b+c)²=a²+b²+c²+2(ab+bc+ca)
9²=a²+b²+c²+2(26)
81=a²+b²+c²+52
a²+b²+c²=81-52
a²+b²+c²=29