Упростите выражения: 1) 6x (2x - 1) - 7x 2) 2 (5x - 4y + 1) - 3 (3x - 3y +1) 3) a + b + c - (a - b - c) 4) 7 (2a + 5b) - 5 (3b - 4a) 5) 8 (3x - 2y) - 7 (y+x) 6) -2 (a - 3b) + 3 (b - 2a)

1) 6x(2x-1)-7x= 12x²-6x-7x= 12x²-13x 2) 2 (5x - 4y + 1) - 3 (3x - 3y +1)= 10x-9x-8y+9y-1= x+y-1. 3) a + b + c - (a - b - c)= 2b+2c 4) 7 (2a + 5b) - 5 (3b - 4a)= 20a+14a-15b+35b= 34a+20b 5) 8 (3x - 2y) - 7 (y+x)= -7x-7y +24x-16y= 17x-23y 6) -2 (a - 3b) + 3 (b - 2a)= -6a-2a+9b= -8a+9b