Выполните действия

(3a-7b) ^2-42ab

81x^2 - (9x+7y) ^2

X (x-7) + (x+3) ^2

(y-5) ^2 - (y-2) 5y

1) (3a-7b) ^2-42ab

9a^2-42ab+49b^2-42ab

9a^2-84ab+49b^2

2) 81x^2 - (9x+7y) ^2

(9x - (9x+7y)) * (9x + (9x+7y))

(9x-9x-7y) * (9x+9x+7y)

(-7y) * (18x+7y)

-7y * (18x+7y)

3) x (x-7) + (x+3) ^2

x^2-7x+x^2+6x+9

2x^2-x+9

4) (y-5) ^2 - (y-2) 5y

y^2-10y+25 - (5y^2-10y)

y^2-10y+25-5y^2+10y

-4y^2+25