Verified answer

2a) - 36c - 3(5 - 6c)² = - 36c - 3(25 - 60c + 36c²) = - 36c - 75 + 180c - 108c²=

= - 108c² + 144c - 75

2б) (7b - 1)(1 + 7b) - b(4 - 3b) = 49b² - 1 - 4b + 3b² = 52b² - 4b - 1

2в) (2k - 3)(3 + 2k) - (3k - 5)² - 30k = 4k² - 9 - 9k² + 30k - 25 - 30k =

= - 5k² - 34

3a) x² - (x - 4)(x + 4) = 2x

x² - x² + 16 = 2x

2x = 16

x = 8

3б) (3y + 1)² - 9(y + 1)(y - 1) = 8y - 16

9y² + 6y + 1 - 9(y² - 1) = 8y - 16

9y² + 6y + 1 - 9y² + 9 = 8y - 16

6y + 10 = 8y - 16

8y - 6y = 10 + 16

2y = 26

y = 13