a)(x+y+z)(z-y+z) b)(x-y-z)(x+y+z) c)(x-y+z)(x+y-z) d)(a+b-c)(b+c-a) e)(a+b-c)(b+c-a) HỨA VOTE 5 SAO 23/08/2021 Bởi Melanie a)(x+y+z)(z-y+z) b)(x-y-z)(x+y+z) c)(x-y+z)(x+y-z) d)(a+b-c)(b+c-a) e)(a+b-c)(b+c-a) HỨA VOTE 5 SAO
`a) (x+y+z)(z-y+z)` `= xz- xy + xz + yz – y^2 + yz + z^2 – yz + z^2` `= 2xz – xy + yz – y^2 + 2z^2` `b) (x-y-z)(x+y+z)` `= x^2 + xy + xz – xy +y^2 + yz – xz + yz + z^2` `= x^2 + y^2 + 2yz + z^2` `c) (x-y+z)(x+y-z)` `= x^2 + xy – xz – xy + y^2 – yz + xz + yz – z^2` `= x^2 + y^2 – z^2` `d) (a+b-c)(b+c-a)` `= ab + ac – a^2 + b^2 + bc – ab – bc + c^2 – ac` `= -a^2 + b^2 + c^2` `\text{Bài e) giống d) nên mình khỏi cần làm nha!}` Bình luận
`a) (x+y+z)(z-y+z)`
`= xz- xy + xz + yz – y^2 + yz + z^2 – yz + z^2`
`= 2xz – xy + yz – y^2 + 2z^2`
`b) (x-y-z)(x+y+z)`
`= x^2 + xy + xz – xy +y^2 + yz – xz + yz + z^2`
`= x^2 + y^2 + 2yz + z^2`
`c) (x-y+z)(x+y-z)`
`= x^2 + xy – xz – xy + y^2 – yz + xz + yz – z^2`
`= x^2 + y^2 – z^2`
`d) (a+b-c)(b+c-a)`
`= ab + ac – a^2 + b^2 + bc – ab – bc + c^2 – ac`
`= -a^2 + b^2 + c^2`
`\text{Bài e) giống d) nên mình khỏi cần làm nha!}`