Question

помогите пожалуйста. Очень надо​

Answer 1

1

${( *+ 2a)}^{2} = * + 12ab + * \\ (a+b)^{2}=a^{2}+2ab+b^{2}\\ 12ab = 2 \times 2a \times 3b = >$

=> 3b - второе слагаемое

${(3b + 2a)}^{2} = {(3b)}^{2} + 12ab + (2a) {}^{2} = \\ = 9 {b}^{2} + 12ab + 4a {}^{2}$

2.

${(3x +* )}^{3} = *+ 27 {x}^{2} y +* + *$

${(a + b)}^{3} = {a}^{3} + 3a {}^{2} b + 3ab {}^{2} + b {}^{3}$

$27 {x}^{2} y = 3 \times 9 {x}^{2} \times y = 3 \times {(3x)}^{2} \times y$

у - второе слагаемое

${(3x + y)}^{2} = {(3x)}^{3} + 27 {x}^{2} y + 3 \times {y}^{2} \times 3x + {y}^{3} = \\ = 27 {x}^{3} + 27 {x}^{2} y + 3x {y}^{2} + {y}^{3}$