Question

Решите всё плиз прошу вас​

Answer 1

2)
$(3 + x)(x - 3) - {(3 - x)}^{2} = \\ = {x}^{2} - 9 - (9 - 6x + {x}^{2} ) = \\ = {x}^{2} - 9 - 9 + 6x - {x}^{2} = \\ = 6x - 18$
${(2x - 4)}^{2} - {(2x + 3)}^{2} = \\ = 4 {x}^{2} - 16x + 16 - \\ - (4 {x}^{2} + 12x + 9) = \\ = 4 {x}^{2} - 16x + 16 - \\ - 4 {x}^{2} - 12x - 9 = \\ = - 28x + 7$
3)
${(x - y)}^{3} = {x}^{3} - {y}^{3} - 3xy(x - y) \\ {x}^{3} - 3 {x}^{2} y + 3x {y}^{2} - {y}^{3} = \\ = {x}^{3} - {y}^{3} - 3 {x}^{2} y + 3x {y}^{2}$
Получили, что левая часть равна правой, а значит имеем тождество.

4)
${37}^{2} + 2 \times 37 \times 13 + {13}^{2} = \\ = {(37 + 13)}^{2} = {50}^{2} = 2500$