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b) \(9x^2+90x+225-\left(x-7\right)^2\)
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\(=\left(3x+15\right)^2-\left(x-7\right)^2=\left(4x+8\right)\left(2x+22\right)=8\left(x+2\right)\left(x+11\right)\)
(x-7)^2 = x^2-14x+49
<=> 9x^2+90x+225 -x^2+14x-49
= 8x^2+104x+176
= 8(x^2+13+22)
<=> 8(x+2)(x+11)
9x2+90x+225-(x-7)2
=(3x+15)2-(x-7)2
=(3x+15-x+7)(3x+15+x-7)
=(2x+22)(4x+8)
=2 (x+11)4 (x+2)
=8 (x+11)(x+2)
9x2+90x+225-(x-7)2
=(3x)2+2.3x.15+152-(x-7)2
=(3x+15)2-(x-7)2
=[(3x+15)-(x-7)][(3x+15)+(x-7)]
=(3x+15-x+7)(3x+15+x-7)
=(2x+22)(4x+8)
=2(x+11).4(x+2)
=8(x+11)(x+2)
\(\left(x^2+2x\right)^2+4\left(x^2+2x\right)+5\left(x^2+2x\right)+20\)
\(=\left(x^2+2x\right)\left(x^2+2x+4\right)+5\left(x^2+2x+4\right)\)
\(=\left(x^2+2x+5\right)\left(x^2+2x+4\right)\)
\(x^6+y^6=\left(x^2\right)^3+\left(y^2\right)^3=\left(x^2+y^2\right).\left(x^4-x^2y^2+y^4\right)\\ ---\\ 0,04-9x^2=\left(0,2\right)^2-\left(3x\right)^2=\left(0,2-3x\right)\left(0,2+3x\right)\\ ---\\ 32x^2-2\left(y-1\right)^2=2\left[16x^2-\left(y-1\right)^2\right]=2\left[\left(4x\right)^2-\left(y-1\right)^2\right]\\ =2\left(4x-y+1\right)\left(4x+y-1\right)\)
Câu 2 nha
\(a,x^4+2x^3+x^2\)
\(=x^2\left(x^2+2x+1\right)\)
\(=x^2\left(x+1\right)^2\)
\(c,x^2-x+3x^2y+3xy^2+y^3-y\)
\(=\left(x^3+3x^2y+3xy^2+y^3\right)-\left(x+y\right)\)
\(=\left(x+y\right)^3-\left(x+y\right)\)
\(=\left(x+y\right)\left(x^2+2xy+y^2-1\right)\)
\(A=4x^2+6x=2x\left(2x+3\right)\)
\(B=\left(2x+3\right)^2-x\left(2x+3\right)=\left(2x+3\right)\left(2x+3-x\right)=\left(2x+3\right)\left(x+3\right)\)
\(C=\left(9x^2-1\right)-\left(3x-1\right)^2=\left(3x-1\right)\left(3x+1\right)-\left(3x-1\right)^2=\left(3x-1\right)\left(3x+1-3x+1\right)=2\left(3x+1\right)\)
\(D=x^3-16x=x\left(x^2-16\right)=x\left(x-4\right)\left(x+4\right)\)
\(E=4x^2-25y^2=\left(2x-5y\right)\left(2x+5y\right)\)
\(G=\left(2x+3\right)^2-\left(2x-3\right)^2=\left(2x+3-2x+3\right)\left(2x+3+3x-3\right)=6.4x=24x\)
\(A=2x\left(2x+3\right)\\ B=\left(2x+3\right)\left(2x+3-x\right)=\left(2x+3\right)\left(x+3\right)\\ C=\left(3x-1\right)\left(3x+1\right)-\left(3x-1\right)^2\\ =\left(3x-1\right)\left(3x+1-3x+1\right)\\ =2\left(3x-1\right)\\ D=x\left(x^2-16\right)=x\left(x-4\right)\left(x+4\right)\\ E=\left(2x-5y\right)\left(2x+5y\right)\\ G=\left(2x+3-2x+3\right)\left(2x+3+2x-3\right)\\ =24x\)
9x2 + 90x + 225 - ( x - 7 )2
= ( 3x + 15 )2 - ( x - 7 )2
= ( 3x + 15 + x - 7 )( 3x + 15 - x + 7 )
= ( 4x + 8 )( 2x + 22 )
= 4( x + 2 ) 2 ( x + 11 )
= 8( x + 2 )( x + 11 )
Hk tốt