a,(a+b+c)^2+(a+b-c)^2
b,(a+b)^3-3(a+b)^2b+3(a+b)b^2-b^3
c,(a^2-b^2)(a^2+ab+b^2)(a^2-ab+b^2)
a,(a+b+c)^2+(a+b-c)^2 b,(a+b)^3-3(a+b)^2b+3(a+b)b^2-b^3 c,(a^2-b^2)(a^2+ab+b^2)(a^2-ab+b^2)
By Aubrey
By Aubrey
a,(a+b+c)^2+(a+b-c)^2
b,(a+b)^3-3(a+b)^2b+3(a+b)b^2-b^3
c,(a^2-b^2)(a^2+ab+b^2)(a^2-ab+b^2)
Đáp án:
Giải thích các bước giải:
a,(a+b+c)²+(a+b-c)²
=a²+b²+c²+2ab+2bc+2ac+a²+b²+c²-2ac-2bc+2ab
=2c²+2b²+4ab+2a²
=2c²+2(a+b)²
b, (a+b)³-3(a+b)²b+3(a+b)·b²-b³
=(a+b-b)³=a³
c, (a²-b²)(a²+ab+b²)(a²-ab+b²)
=[(a-b)(a²+ab+b²)]·[(a+b)(a²-ab+b²)]
=(a³-b³)(a³+b³)
=$a^{6}$ -$b^{6}$
`#DyHungg`
`a) (a+b+c)^2+(a+b-c)^2`
`=(a+b+c)(a+b+c)+(a+b-c)(a+b-c)`
`=a²+c²+b²+2ab+2bc+2ac+a²+b²+c²+2ab-2ac-2bc`
`=2a²+2b²+2c²+4ab`
…………………..
`b) (a+b)³-3(a+b)².b+3(a+b)b²-b³`
`=a³+3a²b+3ab²+b³-3b(a²+2ab+b²)+b²(3a+3b)-b³`
`=a³+3a²b+3ab²+b³-3a²b-6ab²-3b³+3ab²+3b³-b³`
`=a³`
………….
`c) (a²-b²)(a²+ab+b²)(a²-ab+b²)`
`=(a^4+a³b-ab³-b^4)(a²-ab+b²)`
`=a^6-a^5b+a^4b^2+a^5b-a^4b^2+a^3b^3-a³b³+a²b^4-ab^5-a^2b^4+ab^5-b^6`
`=a^6-b^6`