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a) \(4x^2-12x+9=\left(2x\right)^2-2.2x.3+3^2=\left(2x-3\right)^2\)
b) \(4x^2+4x+1=\left(2x\right)^2+2.2x.1+1^2=\left(2x+1\right)^2\)
c) \(1+12x+36x^2=1^2+2.6x.1+\left(6x\right)^2=\left(1+6x\right)^2\)
d) \(9x^2-24xy+16y^2=\left(3x\right)^2-2.3x.4y+\left(4y\right)^2=\left(3x-4y\right)^2\)
f) \(-x^2+10x-25=-\left(x^2-10x+25\right)=-\left(x-5\right)^2\)
g) \(-16a^4b^6-24a^5b^5-9a^6b^4=-\left(16a^4b^6+24a^5b^5+9a^6b^4\right)\)
\(=-\left[\left(4a^2b^3\right)^2+2.4a^2b^3.3a^3b^2+\left(3a^3b^2\right)^2\right]\)
\(=-\left(4a^2b^3+3a^3b^2\right)^2\)
h) \(25x^2-20xy+4y^2=\left(5x\right)^2-2.5x.2y+\left(2y\right)^2\) \(=\left(5x-2y\right)^2\)
i) \(25x^4-10x^2y+y^2=\left(5x^2\right)^2-2.5x^2.y+y^2=\left(5x^2-y\right)^2\)
a) x2 - 16 - 4xy + 4y2
= ( x2 - 4xy + 4y2 ) - 16
= ( x - 2y )2 - 42
= ( x - 2y - 4 )( x - 2y + 4 )
b) x5 - x4 + x3 - x2
= x2( x3 - x2 + x - 1 )
= x2[ x2( x - 1 ) + ( x - 1 ) ]
= x2( x - 1 )( x2 + 1 )
c) x( x + 4 )( x + 6 )( x + 10 ) + 128 < mình nghĩ là nên sửa đề như này :]>
= [ x( x + 10 ) ][ ( x + 4 )( x + 6 ) ] + 128
= ( x2 + 10x )( x2 + 10x + 24 ) + 128
Đặt t = x2 + 10x
bthuc <=> t( t + 24 ) + 128
= t2 + 24t + 128
= t2 + 16t + 8t + 128
= t( t + 16 ) + 8( t + 16 )
= ( t + 16 )( t + 8 )
= ( x2 + 10x + 16 )( x2 + 10x + 8 )
= ( x2 + 2x + 8x + 16 )( x2 + 10x + 8 )
= [ x( x + 2 ) + 8( x + 2 ) ]( x2 + 10x + 8 )
= ( x + 2 )( x + 8 )( x2 + 10x + 8 )
cảm ơn bạn câu c mình chép nhầm nó là 128 đó
b,-16a4b6-24a5b5-9a6b4
= -(16a4b6+24a5b5+9a6b4)
= -(4a2b3+3a3b2)2
= - [a2b2(4b-3a)]2
a) \(4a^3b^3c^2x+12a^3b^4c^2-16a^4b^5cx\)
\(=4a^3b^3c\left(cx+3bc-4ab^2x\right)\)
b) \(\left(b-2c\right)\left(a-b\right)-\left(a+b\right)\left(2c-b\right)\)
\(=\left(b-2c\right)\left(a-b+a+b\right)=2a\left(b-2c\right)\)
c) \(3a\left(a+5\right)-2\left(5+a\right)=\left(a+5\right)\left(3a-2\right)\)
d) \(\left(x+1\right)^2-3\left(x+1\right)=\left(x+1\right)\left(x+1-3\right)\)
\(a^4+a^2+1\)
\(=a^4-a+a^2+a+1\)
\(=a\left(a^3-1\right)+\left(a^2+a+1\right)\)
\(=a\left(a-1\right)\left(a^2+a+1\right)+\left(a^2+a+1\right)\)
\(=\left(a^2+a+1\right)\left[a\left(a-1\right)+1\right]\)
\(=\left(a^2+a+1\right)\left(a^2-a+1\right)\)
a4 + a2 +1 = a4 +2a2 + 1 - a2
= (a4 +2a2 + 1) - a2
= (a2 + 1)2 - a2
= (a2 + 1 - a)(a2 + 1 +a)
\(4x^2-4x-35\) \(=\left(2x\right)^2-2.2x.1+1-36\)
\(=\left(2x-1\right)^2-6^2\)
\(=\left(2x-7\right)\left(2x+5\right)\)
\(18x^2-5x-2\) \(=\left(x-\frac{1}{2}\right)\left(x+\frac{2}{9}\right)\)
\(8x^3-26x^2+13x+5=\) \(8x^3-8x^2-18x^2+18x-5x+5\)
\(=8x^2\left(x-1\right)-18x\left(x-1\right)-5\left(x-1\right)\)
\(=\) \(\left(8x^2-18x-5\right)\left(x-1\right)\)
\(=\left(x-\frac{5}{2}\right)\left(x+\frac{1}{4}\right)\)\(\left(x-1\right)\)
\(4a^4b-24a^3b^2+36a^2b^3\)
\(=4a^2b\left(a^2-6ab+9b^2\right)\)
\(=4a^2b\left[a^2-2.a.3b+3b^2\right]\)
\(=4a^2b\left(a-3b\right)^2\)
\(4a^4b-24a^3b^2+36a^2b^3\)
\(=4a^2b\left(a^2-6ab+9b^2\right)\)
\(=4a^2b\left[a^2-2\cdot a\cdot3b+\left(3b\right)^2\right]\)
\(=4a^2b\left(a-3b\right)^2\)
\(-16a^4b^6-24a^5b^5-9a^6b^4\)
\(=-a^4b^4\left(16b^2+24ab+9a^2\right)\)
\(=-a^4b^4\left[\left(4b\right)^2+2\cdot4\cdot3\cdot ab+\left(3a\right)^2\right]\)
\(=-a^4b^4\cdot\left(3a+4b\right)^2\)