выполнить 4 и 5 даю 40 баллов. Created by danchojobik. algebra-ru

выполнить 4 и 5 даю 40 баллов...

alesyaperova

$1)3(1 + 2xy)(1 - 2xy) = \\ 3(1 - 4 {x}^{2} {y}^{2} ) = 3 - 12 {x}^{2} {y}^{2}$

$2) {a}^{2} + 12a + 36 - ( {a}^{2} - 12a + 36) \\ {a}^{2} + 12a + 36 - {a}^{2} + 12a - 36 = \\ 24a$

$3) {4x}^{2} - 12xy + {9y}^{2}$

$16 {y}^{2} = 49 \\ {y}^{2} = 49 \div 16 = \frac{49}{16} \\ y1 = \frac{7}{4}$

$y2 = - \frac{7}{4}$

2 votes Thanks 1

Universalka

1) 3(1 + 2xy)(1 - 2xy) = 3(1² - (2xy)²) = 3(1 - 4x²y²) = 3 - 12x²y²

2) (a + 6)² - (a - 6)² = (a + 6 - a + 6)(a + 6 + a - 6) = 12 * 2a = 24a

3) (2x - 3y)² = (2x)² - 2 * 2x * 3y + (3y)² = 4x² - 12xy + 9y²

4) 16y² - 49 = 0

(4y)² - 7² = 0

(4y - 7)(4y + 7) = 0

или 4y - 7 = 0 или 4y + 7 = 0

4y = 7 4y = - 7

y₁ = 1,75 y₂ = - 1,75

1 votes Thanks 1

danchojobik почему 2у

Universalka Конечно же 4, а не 2. Исправила.