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4n: 2n+1
= (22)n: 2n+1
= 22n:2n+1
= 22n-n-1
= 2n-1
\(1,\\ a,=\left(x+2\right)\left(x^2-2x+4\right)\\ b,=\left(x-4\right)\left(x^2+8x+16\right)\\ c,=\left(3x+1\right)\left(9x^2-3x+1\right)\\ d,=\left(4m-3\right)\left(16m^2+12m+9\right)\\ 2,\\ a,=x^3+125\\ b,=1-x^3\\ c,=y^3+27t^3\)
a)
\(=\left(x+2\right)\left(x^2-2x+4\right)\)
b)
\(=\left(x-4\right)\left(x^2+4x+16\right)\)
c)=\(\left(3x+1\right)\left(9x^2-3x+1\right)\)
d)
=\(\left(4m-3\right)\left(16m^2+12m+9\right)\)
`9x^2+4y^2-12xy+6x-4y+1`
`=(3x)^2-2.3x.2y+(2y)^2+2(3x-2y)+1`
`=(3x-2y)^2+2(3x-2y)+1`
`=(3x-2y+1)^2`
Lời giải:
a. $-8x+16+x^2=x^2-2.x.4+4^2=(x-4)^2$
b. $xy^2+\frac{1}{4}x^2y^4+1=(\frac{1}{2}xy^2)^2+2.\frac{1}{2}xy^2.1+1^2$
$=(\frac{1}{2}xy^2+1)^2$
a: \(x^2-8x+16=\left(x-4\right)^2\)
b: \(\dfrac{1}{4}x^2y^4+xy^2+1=\left(\dfrac{1}{2}xy^2+1\right)^2\)
1.a) xy + 2y - x2 + 4
= y ( x + 2 ) - ( x2 - 4 ) = y ( x + 2 ) - ( x - 2 ) ( x + 2 ) = ( x + 2 )( y - x + 2 )
b) 2x2 + y2 + 3xy
= ( 2x2 + 2xy ) + ( y2 + xy )
= 2x ( x + y ) + y ( x + y )
= ( x + y ) ( 2x + y )
2.
x - y = 5 \(\Rightarrow\)( x - y )2 = 25 \(\Rightarrow\)x2 + y2 = 25 + 2xy = 25 + 2.3 = 31
A = ( x + y )2 = x2 + y2 + 2xy = 31 + 6 = 37
\(a.9x^2+30x+25=\left(3x+5\right)^2\)
\(b.\frac{12}{5}x^2y^2-9x^4-\frac{4}{25}y^4=-\left(3x^2+\frac{2}{5}y^2\right)\)
\(c.a^2y^2+b^2x^2-2axby=\left(ay-bx\right)^2\)
\(d,64x^2-\left(8a+b\right)^2=\left(8a-8a-b\right)\left(8x+8a+b\right)\)
\(e,100-\left(3x-y\right)^2=10^2-\left(3x-y\right)^2=\left(10-3x+y\right)\left(10+3x-y\right)\)
\(g.27x^3-a^3b^3=\left(3x-ab\right)\left(9a^2+3xab+a^2b^2\right)\)
Trả lời:
a, \(9x^2+30x+25=\left(3x\right)^2+2.3x.5+5^2=\left(3x+5\right)^2\)
\(\frac{4}{9}x^4-16x^2=\left(\frac{2}{3}x^2\right)^2-\left(4x\right)^2=\left(\frac{2}{3}x^2-4x\right)\left(\frac{2}{3}x^2+4x\right)\)
c, \(a^2y^2+b^2x^2-2axby=\left(ay\right)^2-2.ay.bx+\left(bx\right)^2=\left(ay-bx\right)^2\)
d, \(64x^2-\left(8a+b\right)^2=\left(8x\right)^2-\left(8a+b\right)^2=\left(8x-8a-b\right)\left(8x+8a+b\right)\)
e, \(100-\left(3x-y\right)^2=10^2-\left(3x-y\right)^2=\left(10-3x+y\right)\left(10+3x-y\right)\)
f, \(27x^3-a^3b^3=\left(3x\right)^3-\left(ab\right)^3=\left(3x-ab\right)\left(9x^2+3xab+a^2b^2\right)\)