a,
-(59-3x)+39
=-59+3x+39
=3x-20=VP
b,c,d làm tương tự nha
hok tốt
a) ta có: -(59-3x)+39=-59+3x+39=(-59+39)+3x=-20+3x=3x-20
b,c) phá ngoặc như câu a
d) -(a+b+c)+(b-c)-(a-c+1)=-a-b-c+b-c-a+c-1=(-a-a)-(b-b)-(c+c-c)-1=-2a-c-1=c-2a-1
kb nha
a/-(59-3x)+39
= -59 + 3x + 39
= 3x + ( -59 + 39 )
=3x - 20 ( đpcm)
b/ -(a+b+c) +(b-c) - (a-c-1)
= -a - b - c + b - c -a + c + 1
= 1 + ( -c-c+c)+( -a - a) +( -b + b)
= 1 + c - 2a ( đpcm)
c/sửa đề:
-(19-2x)+39
-= -19 + 2x + 39
= 2x + 20 ( đpcm)
d/ -(a+b+c) +(b-c) - (a-c+1)
= -a - b - c + b -c -a + c -1
= c - 2a -1( đpcm)
hok tốt!!