a) – ( – a + c – d ) – ( c – a + d ) ; b) – ( a + b – c + d ) + ( a – b – c –d )
c) a( b – c – d ) – a ( b + c – d ) ; d*)(a+ b) ( c + d) – ( a + d ) ( b + c )
e*)( a + b ) ( c – d ) – ( a – b ) ( c + d ) ; f*) ( a + b ) 2 – ( a – b ) 2
Giúp mình với, mình cần gấp
a) -(-a+c-d)-(c-a+d)=a-c+d-c+a-d=2a-2c
b) -(a+b-c+d)+(a-b-c-d)=-a-b+c-d+a-b-c-d=-2b-2d
c) a(b-c-d)-a(b+c-d)=ab-ac-ad-ab-ac+ad=-2ac
d) (a+b)(c+d)-(a+d)(b+c)=ac+ad+bc+bd-ab-ac-bd-cd=ad+bc-ab-bd
e) (a+b)(c-d)-(a-b)(c+d)=ac-ad+bc-bd-ac-ad+bc+bd=-2ad+2bc
f) 2(a+b)-2(a-b)=2a+2b-2a+2b=4b
` – ( – a + c – d ) – ( c – a + d )`
`=a-c+d-c+a-d`
`=(a+a)-(c+c)+(d-d)`
`=2a-2c.`
`( a + b – c + d ) + ( a – b – c –d )`
`=a+b-c+d+a-b-c-d`
`=(a+a)+(b-b)-(c+c)+(d-d)`
`=2a-2c.`
`a( b – c – d ) – a ( b + c – d )`
`=a[( b – c – d )- ( b + c – d )]`
`=a(b-c-d-b-c+d)`
`=a[(b-b)-(c+c)+(d-d)]`
`=a.(-2c)`
`=-2ac.`
`(a+ b) ( c + d) – ( a + d ) ( b + c )`
`=(ac+ad+bc+bd)-(ab+ac+db+dc)`
`=ac+ad+bc+bd-ab-ac-db-dc`
`=(ac-ac)+(bd-bd)+(ad+bc-ab-cd)`
`=ad+bc-ab-cd.`
`( a + b ) ( c – d ) – ( a – b ) ( c + d )`
`=(ac-ad+bc-bd)-(ac+ad-bc-bd)`
`=ac-ad+bc-bd-ac-ad+bc+bd`
`=(ac-ac)-(ad+ad)+(bc+bc)+(bd-bd)`
`=2bc-2ad.`
`( a + b )^ 2 – ( a – b )^2`
`=a^2+2ab+b^2-(a^2-2ab+b^2)`
`=a^2+2ab+b^2-a^2+2ab-b^2`
`=(a^2-a^2)+(b^2-b^2)+(2ab+2ab)`
`=4ab.`