jawab donk yg baik tolong bantu no 13 aja

a. 5x-2x = 3x
b. 9 + 4x - 1 = 4x + (9-1)
= 4x + 8
c. 4x - 8x + 12 = (4x-8x) +12
= -4x + 12
d. 7 - 2x - x + 5 = ( 7 + 5 ) + (-2x-x)
= 12 - 3 x
e. 3x2 + 3y2 - 5xy + 2x2 - 5y2 + 6xy
= (3x2 + 2x2) + (3y2 - 5y2) + ( - 5xy + 6xy)
= 5x2 - 2y2 + xy

a. 5x -3x = 2x
b. 9 + 4x-1 = 4x+9-1 = 4x+8
c.4x-8x+12 = -4x+12
d. 7-2x-x+5 = -2x - x +7+5 = -3x+12
e. 3x² + 3y² -5xy+2x²-5y²+6xy = 3x²+2x²+3y²-5y²-5xy+6xy = 5x²-2y²+xy