примеры не сложные 7 класс с меня
a) (a – 4)(a + 3);
b) (x – 2)(x – 5);
c) (2a – 1)(a + 3) – a^2;
d) ( - 2y + 5)(1 – y) + 7y;
e) (3a – 2)(6 – a) + 2a^2;
f) (5 – 2x)(3x – 2) + 6x^2;
g) (2 + y)(4 – 2y – y^2) + 4y^2;
h) x^2 + 16 – (x – 2)(x – 8);
i) 10y^2 – (5y – 1)(3 + 2y).

a) (a – 4)(a + 3) = a²+3a-4a-12 = a²-a-12

b) (x – 2)(x – 5) = x² - 5x - 2x +10 = x² - 7x + 10

c) (2a – 1)(a + 3) – a² = 2a²+ 6a - a - 3 -a² = a² + 5a - 3

d) ( - 2y + 5)(1 – y) + 7y = -2y +2y² + 5 - 5y + 7y = 2y²+5

e) (3a – 2)(6 – a) + 2a² = 18a - 3a² - 12 + 2a + 2a² = -a² + 20a - 12

f) (5 – 2x)(3x – 2) + 6x² = 15x - 10 - 6x² +4x + 6x² = 19x - 10

g) (2 + y)(4 – 2y – y²) + 4y² = 8 - 4y - 2y² + 4y - 2y² - y³ + 4y²  = - y³ + 8

h) x² + 16 – (x – 2)(x – 8) = x² + 16 – ( x² - 8x - 2x + 16 ) = x² + 16 –  x² + 8x + 2x - 16 = 10x

i) 10y² – (5y – 1)(3 + 2y) = 10y² – (15y + 10y² - 3 - 6y) = 10y² – 15y - 10y² + 3 + 6y = -9y + 3