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\(3x\cdot\left(x-y\right)^2-6\cdot\left(y-x\right)\)
\(=3x\left(x-y\right)^2+6\left(x-y\right)\)
\(=\left(x-y\right)\left[3x\left(x-y\right)+6\right]\)
\(=\left(x-y\right)\left(3x^2-3xy+6\right)\)
x⁸ + x⁴ + 1
= x⁸ + 2x⁴ + 1 - x⁴
= (x⁴ + 1)² - x⁴
= (x⁴ + 1)² - (x²)²
= (x⁴ + 1 + x²)(x⁴ + 1 - x²)
= (x⁴ + x² + 1)(x⁴ - x² + 1)
\(\left(x-y\right)^3-\left(x+y\right)^3\\ =\left(x-y-x-y\right)\left(\left(x-y\right)^2+\left(x-y\right)\left(x+y\right)+\left(x+y\right)^2\right)\\ =-2y\left(x^2-2xy+y^2+x^2-y^2+x^2+2xy+y^2\right)\\ =-2y\left(3x^2+y^2\right)\)
\(\left(x-y\right)^3+\left(x+y\right)^3\\ =\left(x-y+x+y\right)\left(\left(x-y\right)^2-\left(x-y\right)\left(x+y\right)+\left(x+y\right)^2\right)\\ =2x\left(x^2-2xy+y^2-\left(x^2-y^2\right)+x^2+2xy+y^2\right)\\ =2x\left(x^2-2xy+y^2-x^2+y^2+x^2+2xy+y^2\right)\\ =2x\left(x^2+3y^2\right)\)
=(x-y-2y)[(x-y)^2+2y(x-y)+4y^2]
=(x-3y)(x^2-2xy+y^2+2xy-2y^2+4y^2)
=(x-3y)(x^2+3y^2)
\(\left(x-y\right)^3-8y^3\)
\(=\left(x-y\right)^3-\left(2y\right)^3\)
\(=\left[\left(x-y\right)-2y\right]\left[\left(x-y\right)^2+2y\left(x-y\right)+\left(2y\right)^2\right]\)
\(=\left(x-y-2y\right)\left(x^2-2xy+y^2+2xy-2y^2+4y^2\right)\)
\(=\left(x-3y\right)\left(x^2+3y^2\right)\)
(x^2+1)^2 - 4x(1-x^2)
=(x^2-1)^2 + 4x^2 + 4x(x^2-1)
(=(x^2-1+2x)^2
=((x-1)^2)^2
=(x-1)^4
casio fx 570 thì ấn mode => 5 => 3 sau điền hệ số a;b;c
casio fx 580 thì ấn mode => 9 => 2 => 2 => điền hệ số a;b;c
có cả cách này à =)))
menu setup -> 9 -> 2 - > 2 (pt cần phân tích) -> nhập hệ số của pt vào từng biến thích hợp -> ''=''
VD : \(A=x^2+4x-5\)có nghiệm \(x_1=1;x_2=-5\)
vậy đa thức cần phân tích là : \(\left(x-1\right)\left(x+5\right)=x^2+5x-x-5\)
Vậy \(A=x^2+4x-5=x^2+5x-x-5=\left(x-1\right)\left(x+5\right)\)
tương tự nhé
19) Ta có: \(-x^2-4x-4\)
\(=-\left(x^2+4x+4\right)\)
\(=-\left(x+2\right)^2\)
20) Ta có: \(-4x^2-12x-9\)
\(=-\left(4x^2+12x+9\right)\)
\(=-\left(2x+3\right)^2\)
21) Ta có: \(-4x^2-4x-1\)
\(=-\left(4x^2+4x+1\right)\)
\(=-\left(2x+1\right)^2\)
22) Ta có: \(-x^2+6x-9\)
\(=-\left(x^2-6x+9\right)\)
\(=-\left(x-3\right)^2\)
23) Ta có: \(-x^2+10x-25\)
\(=-\left(x^2-10x+25\right)\)
\(=-\left(x-5\right)^2\)
24) Ta có: \(-x^2+8x-16\)
\(=-\left(x^2-8x+16\right)\)
\(=-\left(x-4\right)^2\)
25) Ta có: \(-4x^2+12x-9\)
\(=-\left(4x^2-12x+9\right)\)
\(=-\left(2x-3\right)^2\)
26) Ta có: \(a^2-a+b-b^2\)
\(=\left(a-b\right)\left(a+b\right)-\left(a-b\right)\)
\(=\left(a-b\right)\left(a+b-1\right)\)
13) Ta có: \(y^2-2xy+2x-y\)
\(=y\left(y-2x\right)-\left(y-2x\right)\)
\(=\left(y-2x\right)\left(y-1\right)\)
14) Ta có: \(x-2xy+4y-2\)
\(=x\left(1-2y\right)-2\left(1-2y\right)\)
\(=\left(1-2y\right)\left(x-2\right)\)
15) Ta có: \(x^2-2xy+x-2y\)
\(=x\left(x-2y\right)+\left(x-2y\right)\)
\(=\left(x-2y\right)\left(x+1\right)\)
16) Ta có: \(xy-z-y+xz\)
\(=x\left(y+z\right)-\left(y+z\right)\)
\(=\left(y+z\right)\left(x-1\right)\)
17) Ta có: \(2xy+3z-6y-xz\)
\(=\left(2xy-xz\right)+\left(3z-6y\right)\)
\(=x\left(2y-z\right)-3\left(2y-z\right)\)
\(=\left(2y-z\right)\left(x-3\right)\)
18) Ta có: \(2xy-2z+4y-xz\)
\(=\left(2xy+4y\right)+\left(xz+2z\right)\)
\(=2y\left(x+2\right)+z\left(x+2\right)\)
\(=\left(x+2\right)\left(2y+z\right)\)
\(x^2+x-6=x^2-2x+3x-6=x\left(x-2\right)+3\left(x-2\right)=\left(x-2\right)\left(x+3\right)\)
x2 + x - 6
= x2 - 2x + 3x - 6
= x ( x - 2 ) + 3 ( x - 2 )
= ( x - 2 ) ( x + 3 )