1) (2a+b)(5a-b)-3a(2a+b) = (2a+b)(5a-b) - 3a(2a+b) = 10a^2 - 2ab + 5ab - b^2 - 6a^2 - 3ab = 4a^2 - ab - b^2
2) (2x+7y)(2x-y)-7y(2x-y) = (2x+7y)(2x-y) - 7y(2x-y) = 4x^2 - 2xy + 14xy - 7y^2 - 14x + 7y = 4x^2 + 12xy - 7y^2 - 14x + 7y
3) 2y²(y+3)-4y(y+3) = 2y^3 + 6y^2 - 4y^2 - 12y = 2y^3 + 2y^2 - 12y
4) 27x³(a-4x)-18x²*(4x-a) = 27x³a - 108x^4 - 18x²(4x-a) = 27x³a - 108x^4 - 72x³ + 18ax² = 27x³a - 108x^4 - 72x³ + 18ax²
5) (a+b)(c+d)+c(c+d) = ac + ad + bc + bd + c² + cd = ac + ad + bc + bd + c(c+d)
6) (a-b)²+c*(a-b) = a² - 2ab + b² + ac - bc = a² + c(a-b) - 2ab
7) (a-b)²+a²*(b-a) = a² - 2ab + b² + a²b - a³ = b² + a²b - a³
8) (a-b)³-c(b-a)² = a³ - 3a²b + 3ab² - b³ - c(b² - 2ab + a²) = a³ - 3a²b + 3ab² - b³ - cb² + 2cab - ca² = a³ - 3a²b + 3ab² - b³ - cb² + 2cab - ca²
1) (2a+b)(5a-b)-3a(2a+b) = (2a+b)(5a-b) - 3a(2a+b) = 10a^2 - 2ab + 5ab - b^2 - 6a^2 - 3ab = 4a^2 - ab - b^2
2) (2x+7y)(2x-y)-7y(2x-y) = (2x+7y)(2x-y) - 7y(2x-y) = 4x^2 - 2xy + 14xy - 7y^2 - 14x + 7y = 4x^2 + 12xy - 7y^2 - 14x + 7y
3) 2y²(y+3)-4y(y+3) = 2y^3 + 6y^2 - 4y^2 - 12y = 2y^3 + 2y^2 - 12y
4) 27x³(a-4x)-18x²*(4x-a) = 27x³a - 108x^4 - 18x²(4x-a) = 27x³a - 108x^4 - 72x³ + 18ax² = 27x³a - 108x^4 - 72x³ + 18ax²
5) (a+b)(c+d)+c(c+d) = ac + ad + bc + bd + c² + cd = ac + ad + bc + bd + c(c+d)
6) (a-b)²+c*(a-b) = a² - 2ab + b² + ac - bc = a² + c(a-b) - 2ab
7) (a-b)²+a²*(b-a) = a² - 2ab + b² + a²b - a³ = b² + a²b - a³
8) (a-b)³-c(b-a)² = a³ - 3a²b + 3ab² - b³ - c(b² - 2ab + a²) = a³ - 3a²b + 3ab² - b³ - cb² + 2cab - ca² = a³ - 3a²b + 3ab² - b³ - cb² + 2cab - ca²