Question

wykonaj podane działania a wynik doprowadź do najprostszej postaci:

a) (7x-2y)(-3x+9y-8)=

b) 3a(2a-7) - (2a+1)(3a-4)=

c) 2(a+3)(a-b)+3(b-2)(a-b)=

d) 2 [a-2b-5(3b-4a)]- (a-b)=

e) (2a-3b+1)(8a+b)+9(a-5)=

f) 5x(2-7x)-(3x+4)2x=

g) 6(2-y)(5x+y)+3(x+y)(x-8)=

Answer 1

a) (7x-2y)(-3x+9y-8)= -21x²+63xy-56x+6xy-18y²+16y=-21x²-18y²+69xy-56x+16y

b) 3a(2a-7) - (2a+1)(3a-4)=6a²-21a-(6a²-8a+3a-4)=6a²-21a-6a²+8a-3a+4a=-12a

c) 2(a+3)(a-b)+3(b-2)(a-b)=2(a²-ab+3a-3b)+3(ab-b²-2a+2b)=2a²-2ab+6a-6b+3ab-3b²-6a+6b=2a²-3b²+ab

d) 2 [a-2b-5(3b-4a)]- (a-b)=2(a-2b-15b+20a)-a+b=2a-4b-30b+40a-a+b=41a-33b

e) (2a-3b+1)(8a+b)+9(a-5)=16a²+2ab-24ab-3b²+8a+b+9a-45=16a²-3b²-22ab+17a+b-45

f) 5x(2-7x)-(3x+4)2x=10x-35x²-(6x²+8x)=10x-35x²-6x²-8x=-41x²+2x

g) 6(2-y)(5x+y)+3(x+y)(x-8)=6(10x+2y-5xy-y²)+3(x²-8x+xy-8y)=60x+12y-30xy-6y²+3x²-24x+3xy-24y=3x²-6y²-27xy-24x-12y

Answer 2

a) (7x-2y)(-3x+9y-8)= - 21x² + 63xy - 56x + 6xy - 18y² + 16y =

= -21x² - 18y² - 56x + 16y + 69xy

b) 3a(2a-7) - (2a+1)(3a-4)= 6a² - 21a - 6a² + 8a - 3a + 4 = -16a + 4 = -4(4a -1)

c) 2(a+3)(a-b)+3(b-2)(a-b)= 2a² - 2ab + 6a - 6b + 3ab - 3b² - 6a + 6b =

= 2a² - 3b² - 2ab

d) 2 [a-2b-5(3b-4a)]- (a-b)= 2(a - 2b - 15b + 20a) - a + b = 2a - 4b - 30b + 40a      - a + b = 41a - 33b

e) (2a-3b+1)(8a+b)+9(a-5)= 16a² - 24ab + 8a + 2ab - 3b² + b + 9a - 45 =

= 16a² - 3b² - 22ab + 17a + b - 45

f) 5x(2-7x)-(3x+4)2x= 10x - 35x² - 6x² - 8x = 2x - 41x²

g) 6(2-y)(5x+y)+3(x+y)(x-8)= 60x + 12y - 30xy - 6y² + 3x² - 24x + 3xy - 24y² =

= 3x² - 30y² - 24x + 12y - 27xy