Question

expand ( a + 5b + 4c)²​

Answer 1

$expand \: ( a + 5b + 4c)² \\ \\ ans. \: ( a + 5b + 4c)² = ({a})^{2} + ({5b})^{2} + ({4c})^{2} + 2(a \times 5b + 5b \times 4c + 4c \times a) \\ \\ = > {a}^{2} + {25b}^{2} + {16c}^{2} + 2(5ab + 20bc + 4ac) \\ \\ = > {a}^{2} + {25b}^{2} + {16c}^{2} + 10ab + 40bc + 8ac \: \: ans... \\ \\ \\ formula \: used = > {a}^{2} + {b }^{2} + {c}^{2} + 2(ab + bc + ca)$