Question

a+b=7 and ab=10 what is a^2+b^2

Answer 1

$a + b = 7 \\ ab = 10 \\ \\ {(a + b)}^{2} = {a}^{2} + {b}^{2} + 2ab = {7}^{2} \\ = {a}^{2} + {b}^{2} + 2 \times 10 = 49 \\ = {a}^{2} + {b}^{2} + 20 = 49 \\ = {a}^{2} + {b}^{2} = 49 - 20 \\ = {a}^{2} + {b}^{2} = 29$
Answer is.....29



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