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\(\left(a-b\right)^3-\left(b-a\right)^2+b\left(a-b\right)^2\)
\(=\left(a-b\right)^3-\left(a-b\right)^2+b\left(a-b\right)^2\)
\(=\left(a-b\right)^2.\left(a-b-1+b\right)\)
\(=\left(a-b\right)^2.\left(a-1\right)\)
\(\left(a-b\right)^3-\left(b-a\right)^2+b\left(a-b\right)^2=\left(a-b\right)^3-\left(a-b\right)^2+b\left(a-b\right)^2\)
=\(\left(a-b\right)^2\left(a-b-1+b\right)=\left(a-b\right)^2\left(a-1\right)\)
a) Ta có \(6x^2-15x+9=3.\left(2x^2-5x+3\right)=3.\left(2x^2-2x^2-3x+3\right)\)
\(=3.\left[2x.\left(x-1\right)-3.\left(x-1\right)\right]=3.\left(2x-3\right).\left(x-1\right)\)
b) Ta có \(5x^2+12x+7=5x^2+5x+7x+7=5x.\left(x+1\right)+7.\left(x+1\right)\)
\(=\left(x+1\right)\left(5x+7\right)\)
a) \(6x^2-15x+9\)
\(=3\left(2x^2-5x+3\right)\)
\(=3\left(x-1\right)\left(2x-3\right)\)
b) \(5x^2+12x+7\)
\(=\left(5x^2+5x\right)+\left(7x+7\right)\)
\(=5x\left(x+1\right)+7\left(x+1\right)\)
\(=\left(x+1\right)\left(5x+7\right)\)
a) A = x3+3x2+3x+9
\(=x^2\left(x+3\right)+3\left(x+3\right)=\left(x^2+3\right)\left(x+3\right)\)
b) B = x3-3x2+3x-9
\(=x^2\left(x-3\right)+3\left(x-3\right)=\left(x^2+3\right)\left(x-3\right)\)
c) C = x3-3x2+3x+7
\(=x\left(x^2-3x+3\right)+7\)
a, x^2 - x - y^2 - y
= (x^2 - y^2) - ( x+ y)
= ( x- y)(x+y) - ( x+y )
= ( x - y - 1 )(x+ y)
b, x^2+ 6x + 9 - y^2
= ( x+ 3)^2 - y^2
= ( x+ 3 -y)( x + 3 +y)
\(=a^2\left(1-b^2\right)+b\left(b-1\right)+a\left(b-1\right)..\)
\(=a^2\left(1-b\right)\left(1+b\right)-b\left(1-b\right)-a\left(1-b\right).\)
\(=\left(a^2+a^2b-b-a\right)\left(1-b\right)\)
\(=\left(ab+a+b\right)\left(a-1\right)\left(1-b\right)\)
\(a^2+b^2-a^2b^2+ab-a-b\)
\(=a^2\left(1-b^2\right)+b\left(b-1\right)+a\left(b-1\right)\)
\(=a^2\left(1-b\right)\left(1+b\right)-b\left(1-b\right)-a\left(1-b\right)\)
\(=\left(a^2+a^2b-b-a\right)\left(1-b\right)\)
\(=\left(ab+a+b\right)\left(a-1\right)\left(1-b\right)\)
1, a ( a - b ) ( a + b ) - ( a + b ) ( a2 - ab + b2 )
= ( a + b ) [ a ( a - b ) - ( a2 - ab + b2 )
= ( a + b ) ( a2 - ab - a2 + ab - b2 )
= ( a + b ) b2
.......
2, 3x ( x + 7 )2 - 11x2 ( x + 7 ) + 9 ( x + 7 )
= ( x + 7 ) [( 3x ( x + 7 ) - 11x2 + 9 ]
= ( x + 7 ) ( 3x3 + 21x - 11x2 + 9)
= ( x + 7 ) ( - 8x2 + 21x + 9 )
..........
3, 4x ( x - 2y ) + 8y ( 2y - x )
= 4x ( x - 2y ) - 8y ( x - 2y )
= ( 4x - 8y ) ( x - 2y )
= 4 ( x - 2y ) ( x - 2y )
= 4 ( x - 2y )2
\(a,x^2+2xy-9+y^2\)
\(=x^2+2xy+y^2-9\)
\(=\left(x+y\right)^2-9\)
\(=\left(x+y+9\right)\left(x+y-9\right)\)
\(b,x^4+64\)
\(=\left(x^2\right)^2+16x^2+64-16x^2\)
\(=\left(x^2+8\right)^2-\left(4x\right)^2\)
\(=\left(x^2+8-4x\right)\left(x^2+4x+8\right)\)
a) x2 -2x - 3
= (x2 - 3x) + (x -3)
= x ( x-3) + (x - 3)
= ( x - 3)(x+1)
( Câu này bạn có thể dùng EQN để tính cho nhanh nhé)
b) a4+5a3+15a-9
=(a4-9)+(5a3+15a)
=(a2+3)(a2-3)+5a(a2+3)
=(a2+3)(a2-3+5a)
a) theo đề ta có:
x^2-2x-3=x^2-2x+1-4
=(x-1)^2-2^2
=(x-1-2)(x-1+2)
=(x-3)(x+1)
<=>9*(a+b) ^2-(a+b)
<=> (a+b) *(9*(a+b) -1)
<=> (a+b )*(9a+9b-1)