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E = ac + ad + bc + bd - ab - ac - bd - cd - ad + ab + cd - bc
E = -ab
Kiểm tra lại giúp chị nhé!
E = (a + b) (c + d) - (a + d) (b + c) - (a - c) (d - b)
E = ac + ad + bc + bd - ab - ac - db - dc - ad + ab + cd - cb
E = 0
1) \(a\left(b-c-d\right)-a\left(b+c-d\right)\)
\(=ab-ac-ad-ab-ac+ad\)
\(=-2ac\)
2) \(\left(a+b\right)\left(c+d\right)-\left(a+d\right)\left(b+c\right)\)
\(=ac+ad+bc+bd-ab-ac-bd-cd\)
\(=ad+bc-ab-cd\)
3) \(\left(a+b\right)\left(c-d\right)-\left(a-b\right)\left(c+d\right)\)
\(=ac-ad+bc-bd-ac-ad+bc+bd\)
\(=-2ad+2bc\)
\(=-2\left(ad-bc\right)\)
- A=a+b+c-d-a+b-c+d+a=a+2b
may cau sau tuong tu pha ngoac ra roi rut gon
a,a+b+c-d-a+b-c+d+a=a+2b
b, -a+b-d+b-c+d+c-b-d=-a+b-d
c,a-b-c+d+b+c=a+d
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, \(\left(a+b+c+d\right)-\left(a-b+c-d\right)\)
\(=a+b+c+d-a+b-c+d=2b+2d\)
\(=2.\left(b+d\right)\)
b, \(\left(-a+b-c+d\right)+\left(a+d\right)+\left(-b+c\right)\)
\(=-a+b-c+d+a+d-b+c\)
\(=2d\)
c, \(-\left(a-b-d\right)+\left(b-c+d\right)-\left(-c+b-d\right)\)
\(=-a+b+d+b-c+d+c-b+d\)
\(=-a+b+3d\)
Chúc bạn học tốt!!!
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) = 2b + 2d = 2.(b + d)
b,(-a+b-c+d)+(a+d)+(-b+c) = -a + b - c + d + a + d - b + c = (-a + a) + (b - b) + ( -c + c) + (d + d) = 2d
c,-(a-b-d)+(b-c+d)-(-c+b-d)= -a + b + d + b - c + d + c - b + d = -a + (b + b - b) + (-c + c) + ( d + d + d) = -a + b + 3d
a) -(-a + c - d) - (c - a + d) = a - c + d - c + a - d = (a + a) - (c + c) + (d - d) = 2a - 2c
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) = -2b - 2d
c) (a + b - c) - (b - c + d) = a + b - c - b + c - d = a + (b - b) - (c - c) - d = a - d
d) (b + a) + (c - d) - (c + a) - (b - d) = b + a + c - d - c - a - b + d = (b - b) + (a - a) + (c - c) - (d - d) = 0
e) (a - b) - (d + a) - (c - d) + (c + b) = a - b - d - a - c + d + c + b = (a - a) - (b - b) - (d - d) - (c - c) = 0
f) -a + (c - b) - (c + a - b) = - a + c - b - c - a + b = (-a - a) + (c - c) - (b - b) = -2a
a ) a - c + d - c + a - d = 2a - 2c
b ) -a - b + c - d + a - b - c - d = -2b - 2d
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