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A, (a + b + c - d) - (a + b + c + d)
= a + b + c - d - a - b - c - d
= (a - a) + (b - b) + (c - c) - (d + d)
= 0 + 0 + 0 - 2d
= -2d
Ý b, c em xem lại xem sao chỗ chữ cái viết hoa chỗ lại viết thường là sao em nhỉ?
a, -( -a + c - d) - ( c - d + d) = a - c + d - c + d - d = a + d
b, - ( a+b-c+d) + (a-b-c-d) = -a -b+c-d + a-b-c-d = -2b + (-2c)= -2(b+c)
a) \(\left(a+b-c\right)-\left(b-c+d\right)\)
\(=a+b-c-b+c-d\)
\(=a+b-b-c+c-d\)
\(=a-d\)
b) \(-\left(a-b+c\right)+\left(a-b+d\right)\)
\(=\left(-a\right)+b-c+a+b-d\)
\(=\left(-a\right)+a+b+b-c-d\)
\(=2b-c-d\)
c) \(\left(a+b\right)-\left(-a+b-c\right)\)
\(=a+b+a-b+c\)
\(=a+a+b-b+c\)
\(=2a+c\)
d) \(-\left(a-b-c\right)+\left(a-b-c\right)\)
\(=-a+b+c+a+b+c\)
\(=-a+a+b+b+c+c\)
\(=2b+2c\)
(chắc hơi sai... > . < ...)
1) \(=ac+ad+bc+bd-ab-ac-db-dc=ad+bc-dc-ab=d\left(a-c\right)-b\left(a-c\right)=\left(a-c\right)\left(d-b\right)\)
2) \(=ac-ad+bc-bd-ac-ad+bc+bd=2bc-2ad=2\left(bc-ad\right)\)
3) \(\left(a+b\right)\left(a+b\right)-\left(a-b\right)\left(a-b\right)=a^2+2ab+b^2-a^2+2ab-b^2=4ab\)
a)(a+b)-(a-b)+(a-c)-(a+c)
=a+b-a+b+a-c-a-c
=2b-2c
b)(a+b-c)+(a-b+c)-(b+c-a)-(a-b-c)
=a+b-c+a-b+c-b-c+a-a+b+c
=2a
Giải:
a) A=(a+b)-(a-b)+(a-c)-(a+c)
A=a+b-a+b+a-c-a-c
A=0+(a-a)-c-c
A=0+0-c-c
A=-c-c
b) B=(a+b-c)+(a-b+c)-(b+c-a)-(a-b-c)
B=a+b-c+a-b+c-b-c+a-a+b+c
B=(a+a+a-a)+(b-b-b+b)+(-c+c-c+c)
B=(a+a)+0+0
B=a+a
Chúc bạn học tốt!
1) -a(-a+c-d)-(c-a+d)
=ad-ac+a2-c+a-d
2) -(a+b)-(c+d)+(a-b-c-d)
=-a-b-c-d+a-b-c-d
=-2b-2c-2d
3) a(b-c-a)-a(b+c-d)
=-ac+ab-a2+ad-ac-ab
=ad-2ac-a2
a)-(-a+c-d)-(c-a+d)=a-c+d-c+a-d=(a+a)-(c+c)+(d-d)=2a-2c=2(a-c)
b)-(a+b-c+d)+(a-b-c-d)=-a-b+c-d+a-b-c-d=(-a+a)-(b+b)+(c-c)-(d+d)=0-2b+0-2d=-2(b-d)
c)a(b-c-d)-a(b+c-d)=ab-ac-ad-ab-ac+ad=(ab-ac)-(ac+ac)-(ad-ad)=2ac
d)đề sai
e)(a+b)(c-d)-(a-b)(c+d)=ac+b-ad+b-(ac-b+ad-b)=ac+b-ad+b-ac+b-ad+b=(ac-ac)+(b+b+b+b)-(ad+ad)=4b-2ad=2(2b-ad)
f)(a+b)2-(a-b)2=a2+2ab+b2-(a2-2ab+b2)=a2+2ab+b2-a2+2ab-b2=(a2-a2)+(2ab+2ab)+(b2-b2)=4ab
mk k chắc đâu
1: =a-b+c-a-c=-b
2: =a+b-b+a+c=2a+c
3: =-a-b+c+a-b-c=-2b
4: =ab+ac-ab-ad-ac+ad=0