Question

Bài 17: Viết dưới dạng tích các tổng sau:

1/ ab + ac

2/ ab – ac + ad

3/ ax – bx – cx + dx

4/ a(b + c) – d(b + c)

5/ ac – ad + bc – bd

6/ ax + by + bx + ay

Bài 18: Chứng tỏ

1/ (a – b + c) – (a + c) = -b

2/ (a + b) – (b – a) + c = 2a + c

3/ - (a + b – c) + (a – b – c) = -2b

4/ a(b + c) – a(b + d) = a(c – d)

5/ a(b – c) + a(d + c) = a(b + d)

Giúp mình với nhé

Answer 1

Bài 17 :

1) ab + ac = a ( b + c )

2) ab  - ac + ad = a ( b - c + d )

3) ax - bx - cx + dx = x ( a- b - c + d )

4) a(b + c) – d(b + c) = ( b + c ) ( a - d )

5) ac – ad + bc – bd = a( c - d ) + b ( c - d ) = ( c- d ) ( a + b )

6) ax + by + bx + ay = a( x+ y ) + b ( x + y ) = ( x + y ) (a +b )

Answer 2

Bài 18:

1/ (a – b + c) – (a + c) = a - b + c - a - c = -b

2/ (a + b) – (b – a) + c = a + b - b + a + c = 2a + 2

3/ - (a + b – c) + (a – b – c) = -a -b + c + a - b - c = -2b

4/ a(b + c) – a(b + d) = a ( b + c - b - d ) = a( c - d )

5/ a(b – c) + a(d + c) = a ( b - c + d + c ) = a ( b+ d ) 

Answer 3

Bài 1

1,ab+ac=a.(b+c)

2,ab-ac+ad=a.(b-c+d)

3,ax-bx-cx+dx=x.(a-b-c+d)

4,a.(b+c)-b.(b+c)=(b+c).(a-b)

5,ac-ad+bc-bd=a.(c-d)+b.(c-d)=(c-d).(a+b)

6,ax+by+bx+ay=a.(x+y)+b.(x+y)=(x+y).(a+b)

Bài 2

1,(a-b+c)-(a+c)=-b

 =a-b+c-a-c

 =(a-a)+(c-c)-b

 =0+0-b

 =-b

2,(a+b)-(b-a)+c=2a+c

 =a+b-b+a+c

 =(a+a)+(b-b)+c

 =2a+0+c

 =2a+c

3,-(a+b-c)+(a-b-c)=-2b

 =-a-b+c+a-b-c

 =(-a-a)+[-b+(-b)]+(c-c)

 =0+(-2b)+0

 =-2b

4,a.(b+c)-a.(d+c)=a.(c-d)

   =ab+ac-ab-ad

   =a.(b+c-b-d)

   =a.(c-d)

5,a.(b-c)+a.(d+c)=a.(b+d)

  =ab-ac+ac+ad

  =a.(b-c+c+d)

  =a.(b+d)

Answer 4

Bài 1:

1, ab + ac = a.( b+c )

2. ab - ac + ad = a.( b-c+d )

3. ax - bx - cx + dx = x . ( a-b-c+d )

4,a . ( b+c ) - b . ( b+c ) = ( b+c ) . (a-b )

5, ac - ad + bc - bd = a . ( c-d ) + b . ( c-d ) = ( c-d ) . ( a+b )

6, ax + by + bx + ay = a. ( x+ y ) + b . ( x+y ) = ( x+y ) . ( a+b )