Mọi người giúp mình với
Hãy luôn nhớ cảm ơn và vote 5*
nếu câu trả lời hữu ích nhé!
`1) ( x + 4 )^2 + ( x + 5 )( x - 5 ) - 2x( x + 1 )`
`= x^2 + 8x + 16 + x^2 - 25 - 2x^2 - 2x`
`= 6x - 9`
`2) ( x- 1 )^2 - ( x - 4 )( x+ 4 ) + ( x + 3 )^2`
`= x^2 - 2x + 1 - x^2 + 16 + x^2 + 6x + 9`
`= 4x + 26`
`3) ( x - 1 )^2 - 2( x - 3 )( x + 3 ) + 4x( x - 4 )`
`= x^2 - 2x + 1 - 2( x^2 - 9 ) + 4x^2 - 16x`
`= 5x^2 - 18x + 1 - 2x^2 + 18`
`= 3x^2 - 18x + 19`
`4) ( y - 3 )( y + 3 )( y^2 + 9 ) - ( y^2 + 2 )( y^2 - 2 )`
`= ( y^2- 9 )( y^2 + 9 ) - ( y^2 + 2 )( y^2 - 2) `
`= ( y^4 - 81 ) - ( y^4 - 4 )`
`= y^4 - 81 - y^4 +4`
`= - 77`
`1) ( 2x + 1 )^2 + 2( 2x + 1 ) + 1`
`= ( 2x + 1 + 1 )^2`
`= ( 2x + 2 )^2`
`2) ( 3x - 2y )^2 + 4( 3x - 2y ) + 4`
`= ( 3x - 2y + 2 )^2`
`3) ( x + 3 )^2 + ( x - 2 )^2 - 2( x + 3 )( x - 2 )`
`= ( x + 3 )^2 - 2( x + 3 )( x - 2 ) + ( x - 2 )^2`
`= ( x + 3 - x + 2 )^2`
`= 5^2`
`= 25`
`4) ( 3x - 5 )^2 - 2( 3x - 5 )( 3x + 5 ) + ( 3x + 5 )^2`
`= ( 3x - 5 - 3x - 5 )^2`
`= ( -10 )^2`
`= 100`
`5) ( 3x + 2 )^2 + ( 4x - 1 )^2 + ( 2 + 5x )( 2 - 5x )`
`= 9x^2 + 12x + 4 + 16x^2 - 8x + 1 + 4 - 25x^2`
`= 4x + 9`
`6) ( x + y -z )^2 + 2( x + y - z )( z - y) + ( z - y )^2`
`= ( x + y - z + z - y )^2`
`= x^2`
Hãy giúp mọi người biết câu trả lời này thế nào?
Bài `6`
`1)`
`(x+4)^2+(x+5)(x-5)-2x(x+1)`
`=x^2+8x+16+x^2-25-2x^2-2x`
`=(x^2+x^2-2x^2)+(8x-2x)+(16-25)`
`=6x-9`
`2)`
`(x-1)^2-(x-4)(x+4)+(x+3)^2`
`=x^2-2x+1-(x^2-16)+x^2+6x+9`
`=x^2-2x+1-x^2+16+x^2+6x+9`
`=(x^2-x^2+x^2)+(-2x+6x)+(1+16+9)`
`=x^2+4x+26`
`3)`
`(x-1)^2-2(x-3)(x+3)+4x(x-4)`
`=x^2-2x+1-2(x^2-9)+4x^2-16x`
`=x^2-2x+1-2x^2+18+4x^2-16x`
`=(x^2-2x^2+4x^2)+(-2x-16x)+(1+18)`
`=3x^2-18x+19`
`4)`
`(y-3)(y+3)(y^2+9)-(y^2-2)(y^2+2)`
`=(y^2-9)(y^2+9)-(y^4-4)`
`=y^4-81-y^4+4`
`=-77`
Bài `7`
`1)`
`(2x+1)^2+2(2x+1)+1`
`=(2x+1)^2+2·(2x+1)·1+1^2`
`=(2x+1+1)^2`
`=(2x+2)^2`
`=4x^2+8x+4`
`2)`
`(3x-2y)^2+4(3x-2y)+4`
`=(3x-2y)^2+2·(3x-2y)·2+2^2`
`=(3x-2y+2)^2`
`3)`
`(x+3)^2+(x-2)^2-2(x+3)(x-2)`
`=(x+3)^2-2(x+3)(x-2)+(x-2)^2`
`=[(x+3)-(x-2)]^2`
`=(x+3-x+2)^2`
`=5^2`
`=25`
`4)`
`(3x-5)^2-2(3x-5)(3x+5)+(3x+5)^2`
`=[(3x-5)-(3x+5)]^2`
`=(3x-5-3x-5)^2`
`=(-10)^2`
`=100`
`5)`
`(3x+2)^2+(4x-1)^2+(2+5x)(2-5x)`
`=9x^2+12x+4+16x^2-8x+1+4-25x^2`
`=(9x^2+16x^2-25x^2)+(12x-8x)+(4+1+4)`
`=4x+9`
`6)`
`(x+y-z)^2+2(x+y-z)(z-y)+(z-y)^2`
`=(x+y-z+z-y)^2`
`=x^2`
Hãy giúp mọi người biết câu trả lời này thế nào?
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