k

\(30xy-16x^2-9y^2\)

\(=-\left(16x^2-24xy+9y^2\right)+6xy\)

\(=-\left(4x-3y\right)^2+6xy\)

\(=-\left[\left(4x-3y\right)^2-6xy\right]\)

\(=-\left(4x-3y-\sqrt{6xy}\right)\left(4x-4y+\sqrt{6xy}\right)\)

Lê Tài Bảo ChâuLỡ x,y trái dấu thì sao?

\(30xy-16x^2-9y^2\)

\(=24xy-9y^2-16x^2+6xy\)

\(=3y\left(8x-3y\right)-2x\left(8x-3y\right)\)

\(=\left(3y-2x\right)\left(8x-3y\right)\)

a, \(m^2-n^2=\left(m-n\right)\left(m+n\right)\)

b, \(4m^2-16n^2=\left(2m-4n\right)\left(2m+4n\right)=4\left(m-2n\right)\left(m+2n\right)\)

c, \(49-16x^2=\left(7-4x\right)\left(7+4x\right)\)

d, \(25-9y^2=\left(5-3y\right)\left(5+3y\right)\)

e, \(81x^2-16y^2=\left(9x-4y\right)\left(9x+4y\right)\)

a.

$x^2+20x+100=(x+10)^2$

b.

$16x^2+24xy+9y^2=(4x+3y)^2$

c.

$y^2-14y+49=(y-7)^2$
d.

$9x^2-42xy+49y^2=(3x-7y)^2$

e.

$4x^2-9y^2=(2x-3y)(2x+3y)$

f.

$16-x^2=(4-x)(4+x)$

g.

$49x^2-1=(7x-1)(7x+1)$

h.

$16x^2-25=(4x-5)(4x+5)$

i.

$8x^3+24x^2y+54xy^2+27y^3=(2x+3y)^3$

k.

$x^3-6x^2y+12xy^2-8y^3=(x-2y)^3$

l.

$(2a+b)(4a^2-2ab+b^2)=(2a)^3+b^3=8a^3+b^3$

m.

$(3x-4y)(9x^2+12xy+16y^2)=(3x)^3-(4y)^3=27x^3-64y^3$

a: \(\left(3x-1\right)\left(9x^2+3x+1\right)=27x^3-1\)

b: \(\left(1-\dfrac{x}{5}\right)\left(\dfrac{x^2}{25}+\dfrac{x}{5}+1\right)=1-\dfrac{x^3}{125}\)

c: \(\left(x+3y\right)\left(x^2-3xy+9y^2\right)=x^3+27y^3\)

d: \(\left(4x+3y\right)\left(16x^2-12xy+9y^2\right)=64x^3+27y^3\)

\(a,=\left(x+\dfrac{5}{2}\right)^2\\ b,=\left(2x+3y\right)^2\\ c,=a^2+b^2+c^2+2ab-2bc-2ac\\ d,=\left(4x-1\right)^2\\ e,=a^2+b^2+c^2+2ab+2bc+2ac\\ f,=a^2+b^2+c^2-2ab+2bc-2ac\)

Chọn D

\(4xy^2-6+8y\)

\(4xy^2-6+8y\)