phân tích các đa thức sau thành nhân tử
\(\left(a^2+b^2-5\right)^2-2\left(ab+2\right)^2\)
Phân tích các đa thức sau thành nhân tử:
\(4b^2c^2-\left(b^2+c^2-a^2\right)^2\)
\(\left(a^2+b^2-5\right)^2-4\left(ab+2\right)^2\)
\(4b^2c^2-\left(b^2+c^2-a^2\right)^2\)
\(=\left(2bc-b^2-c^2+a^2\right)\left(2bc+b^2+c^2-a^2\right)\)
\(=\left[a^2-\left(b^2-2bc+c^2\right)\right].\left[\left(b^2+2bc+c^2\right)-a^2\right]\)
\(=\left[a^2-\left(b-c\right)^2\right].\left[\left(b+c\right)^2-a^2\right]\)
\(=\left(a-b+c\right)\left(a+b-c\right)\left(b+c-a\right)\left(b+c+a\right)\)
\(\left(a^2+b^2-5\right)^2-4\left(ab+2\right)^2\)
\(=\left(a^2+b^2-5-2ab-4\right)\left(a^2+b^2-5+2ab+4\right)\)
\(=\left[\left(a-b\right)^2-3^2\right].\left[\left(a+b\right)^2-1\right]\)
\(=\left(a-b-3\right)\left(a-b+3\right)\left(a+b-1\right)\left(a+b+1\right)\)
Tham khảo nhé~
Phân tích các đa thức sau thành nhân tử :
a) \(\left(a^2+b^2-5\right)^2-2\left(ab+2\right)^2\)
b) \(\left(4a^2-3a-18\right)^2-\left(4a^2+3a\right)^2\)
a) \(\left(a^2+b^2-5\right)^2-2\left(ab+2\right)^2\)
\(=\left(a^2+b^2-5\right)^2-\left(\sqrt{2}.ab+\sqrt{2}.2\right)^2\)
\(=\left(a^2+b^2-5-\sqrt{2}.ab-\sqrt{2}.2\right).\left(a^2+b^2-5+\sqrt{2}.ab+\sqrt{2}.2\right)\)
b) \(\left(4a^2-3a-18\right)^2-\left(4a^2+3a\right)^2\)
\(\left(4a^2-3a-18-4a^2-3a\right).\left(4a^2-3a-18+4a^2+3a\right)\)
\(=\left(-6a-18\right).\left(8a^2-18\right)\)
\(=\left(-6\right).\left(a+3\right).2.\left(4a^2-9\right)\)
\(=\left(-12\right).\left(a+3\right).\left(2a-3\right).\left(2a+3\right)\)
a) Xem lại đề
b) ( 4a2 - 3a - 18 )2 - ( 4a2 + 3a )2
= [ ( 4a2 - 3a - 18 ) - ( 4a2 + 3a ) ][ ( 4a2 - 3a - 18 ) + ( 4a2 + 3a ) ]
= ( 4a2 - 3a - 18 - 4a2 - 3a )( 4a2 - 3a - 18 + 4a2 + 3a )
= ( -6a - 18 )( 8a2 - 18 )
= -6( a + 3 ).2( 4a2 - 9 )
= -12( a + 3 )( 4a2 - 9 )
= -12( a + 3 )( 2a - 3 )( 2a + 3 )
a. ( a2 + b2 - 5 )2 - 2 ( ab + 2 )2
= ( a2 + b2 - 5 )2 - [\(\sqrt{2}\)( ab + 2 ) ]2
= [ a2 + b2 - 5 -\(\sqrt{2}\)( ab + 2 ) ] [ a2 + b2 - 5 +\(\sqrt{2}\)( ab + 2 ) ]
= ( a2 + b2 - 5 -\(\sqrt{2}\)ab - 2\(\sqrt{2}\)) ( a2 + b2 - 5 +\(\sqrt{2}\)ab + 2\(\sqrt{2}\) )
b. ( 4a2 - 3a - 18 )2 - ( 4a2 + 3a )2
= ( 4a2 - 3a - 18 - 4a2 - 3a ) ( 4a2 - 3a - 18 + 4a2 + 3a )
= ( - 6a - 18 ) ( 8a2 - 18 )
= - 6 ( a + 3 ) . 2 [ ( 2a )2 - 32 ]
= - 12 ( 2a - 3 ) ( 2a + 3 )
Hãy hoàn thành biến đổi sau vào vở để phân tích đa thức thành nhân tử:
\({a^2} + ab + 2a + 2b = \left( {{a^2} + ab} \right) + \left( {2a + 2b} \right) = ...\)
Em có thể biến đổi theo cách khác để phân tích đa thức trên thành nhân tử không?
`a^2 + ab + 2a + 2b = a(a+2) + b(a+2) = (a+b)(a+2)`
Phân tích đa thức thành nhân tử:
a, \(\left(ax+by\right)^2-\left(ay+bx\right)^2\)
b, \(\left(a^2+b^2-5\right)^2-4\left(ab+2\right)^2\)
\(\left(ax+by\right)^2-\left(ay+bx\right)^2\)
\(=\left(ax+by+ay+bx\right)\left(ax+by-ay-bx\right)\)
\(=\left[a\left(x+y\right)+b\left(x+y\right)\right]\left[a\left(x-y\right)-b\left(x-y\right)\right]\)
\(=\left(a+b\right)\left(a-b\right)\left(x+y\right)\left(x-y\right)\)
\(\left(a^2+b^2-5\right)^2-4\left(ab+2\right)^2\)
\(=\left[\left(a^2+b^2-5\right)+2\left(ab+2\right)\right]\left[\left(a^2+b^2-5\right)-2\left(ab+2\right)\right]\)
\(=\left[a^2+b^2-5+2ab+4\right]\left[a^2+b^2-5-2ab-4\right]\)
\(=\left[\left(a+b\right)^2-1\right]\left[\left(a-b\right)^2-9\right]\)
\(=\left(a+b-1\right)\left(a+b+1\right)\left(a-b-3\right)\left(a-b+3\right)\)
a)
(ax+by)2 - (ay+bx)2
=(ax+by-ay-bx)(ax+by+ay+bx)
=[ a(x-y) -b(x-y)][ a(x+y) + b(x+y)]
=(a-b)(x-y)(a+b)(x+y)
b)(a2+b2-5)2 - 4(ab+2)2
=(a2+b2-5-2ab-4)(a2+b2-5+2ab+4)
=[ (a-b)2 -9][ (a+b)2 -1]
=(a-b-3)(a-b+3)(a+b-1)(a+b+1)
a, \(\left(ax+by\right)^2-\left(ay+bx\right)^2\)
\(=\left(ax+ay+bx+by\right)\left(ax-ay+bx-by\right)\)
\(=\left(a+b\right)\left(x+y\right)\left(a-b\right)\left(x-y\right)\)
b, \(\left(a^2+b^2-5\right)^2-4\left(ab+2\right)^2\)
\(=\left(a^2+b^2-5-2ab-4\right)\left(a^2+b^2-5+2ab+4\right)\)
\(=\left[\left(a-b\right)^2-9\right]\left[\left(a+b\right)^2-1\right]\)
\(=\left(a-b-3\right)\left(a-b+3\right)\left(a+b+1\right)\left(a+b-1\right)\)
Phân tích các đa thức sau thành nhân tử:
\(c,\left(ab+1\right)^2-\left(a+b\right)^2\)
\(d,x^2-2x-4y^2-4y\)
\(\left(ab+1\right)^2-\left(a+b\right)^2=\left(ab+1+a+b\right)\left(ab+1-a-b\right).\)
\(=\left(a+1\right)\left(b+1\right)\left(a-1\right)\left(b-1\right)\)
\\(x^2-2x-4y^2-4y=\left(x^2-2x+1\right)-\left(4y^2+4y+1\right)=\left(x-1\right)^2-\left(2y+1\right)^2\)
\(=\left(x+1+2y+1\right)\left(x+1-2y-1\right)=\left(x+2y+2\right)\left(x-2y\right)\)
Phân tích đa thức thành nhân tử:
\(\left[4abcd\left(a^2+b^2\right)\left(c^2+d^2\right)\right]^2-4\left[cd\left(a^2+b^2\right)+ab\left(c^2+d^2\right)\right]^2\)
Phân tích đa thức thành nhân tử:
\(a\left(b^2+c^2+bc\right)+b\left(c^2+a^2+ac\right)+c\left(a^2+b^2+ab\right)\)
\(a\left(b^2+c^2+bc\right)+b\left(c^2+a^2+ac\right)+c\left(a^2+b^2+ab\right)\)
\(=ab^2+ac^2+abc+bc^2+ba^2+abc+ac^2+bc^2+abc\)
\(=c^2\left(b+a\right)+\left(b^2+3\text{a}b+a^2\right)c+ab^2+a^2b\)
\(=bc^2+ac^2+b^2c+3\text{a}bc+a^2c+ab^2+a^2b\)
\(=\left(c+b+a\right)\left(bc+ac+ab\right)\)
Phân tích đa thức sau thành nhân tử
\(k,ab\left(a+b\right)-bc\left(b+c\right)-ca\left(c-a\right)\)
\(l,a^2\left(b-c\right)+b^2\left(c-a\right)+c^2\left(a-b\right)\)
Phân tích các đa thức sau thành nhân tử bằng phương pháp đặt nhân tử chung:
a) \(4y\left(x-1\right)-\left(1-x\right)\)
b) \(3x\left(z+2\right)+5\left(-x-2\right)\)
a, 4y(x-1)-(1-x)
=(x-1)(4y+1)
b,3x(z+2)+5(-x-2)
=3x(z+2)-5(x+2)
=(z+2)(3x-5)
Phân tích các đa thức sau thành nhân tử:
\(A=4x^2+6x\). \(B=\left(2x+3\right)^2-x\left(2x+3\right)\). \(C=\left(9x^2-1\right)-\left(3x-1\right)^2\).
\(D=x^3-16x\). \(E=4x^2-25y^2\). \(G=\left(2x+3\right)^2-\left(2x-3\right)^2\).
\(A=4x^2+6x=2x\left(2x+3\right)\)
\(B=\left(2x+3\right)^2-x\left(2x+3\right)=\left(2x+3\right)\left(2x+3-x\right)=\left(2x+3\right)\left(x+3\right)\)
\(C=\left(9x^2-1\right)-\left(3x-1\right)^2=\left(3x-1\right)\left(3x+1\right)-\left(3x-1\right)^2=\left(3x-1\right)\left(3x+1-3x+1\right)=2\left(3x+1\right)\)
\(D=x^3-16x=x\left(x^2-16\right)=x\left(x-4\right)\left(x+4\right)\)
\(E=4x^2-25y^2=\left(2x-5y\right)\left(2x+5y\right)\)
\(G=\left(2x+3\right)^2-\left(2x-3\right)^2=\left(2x+3-2x+3\right)\left(2x+3+3x-3\right)=6.4x=24x\)
\(A=2x\left(2x+3\right)\\ B=\left(2x+3\right)\left(2x+3-x\right)=\left(2x+3\right)\left(x+3\right)\\ C=\left(3x-1\right)\left(3x+1\right)-\left(3x-1\right)^2\\ =\left(3x-1\right)\left(3x+1-3x+1\right)\\ =2\left(3x-1\right)\\ D=x\left(x^2-16\right)=x\left(x-4\right)\left(x+4\right)\\ E=\left(2x-5y\right)\left(2x+5y\right)\\ G=\left(2x+3-2x+3\right)\left(2x+3+2x-3\right)\\ =24x\)