Question

if a+b+c=5 and ab+bc+ca=10then callculate the value of asuare +B square +c Square

Answer 1

${(a + b + c)}^{2} = {a}^{2} + {b}^{2} + {c}^{2} + 2(ab + bc + ca) \\ \\ {5}^{2} = {a}^{2} + {b}^{2} + {c}^{2} + 2 \times 10 \\ \\ 25 = {a}^{2} + {b}^{2} + {c}^{2} + 20 \\ \\ {a}^{2} + {b}^{2} + {c}^{2} = 25 - 20 \\ \\ {a}^{2} + {b}^{2} + {c}^{2} = 5$