Question

1. преобразуйте выражение а) (2х -5)² и т.д​

Answer 1

$1)a) {(2 x- 5)}^{2} = 4 {x}^{2} - 2 \times 2x \times 5 + {5}^{2} = 4 {x}^{2} - 20x + 25 \\ b) {(3a + \frac{1}{2} {b}^{2} )}^{2} = 9 {a}^{2} + 2 \times 3 a\times \frac{1}{2} {b}^{2} + \frac{1}{4} {b}^{4} = 9 {a}^{2} + 3a {b}^{2} + 0.25 {b}^{4}$

$2)( - x - y) ^{2} = (x + y) {}^{2} \\ ( {( - x)}^{2} - 2 \times ( x) \times ( - y) + ( - y) {}^{2} = {x }^{2} + 2xy + {y}^{2} \\ ( {x}^{2} + 2xy + {y}^{2} ) = {x}^{2} + 2xy + {y}^{2}$

$3)a) {a}^{2} + 2ab + {b}^{2} = (a + b) {}^{2} \\ b) {n}^{2} - 4mn + 4 {m}^{2} = {(n - 2m)}^{2} \\ v)4 {a}^{6} - 8 {a}^{3} b + {b}^{2} = (2 {a}^{3} - b) {}^{2}$

${(28 + 72)}^{2} > {28}^{2} + {72}^{2}$