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6 tháng 9 2018
1/ x^2 +4xy +4y^2 = (x +2y)^2
2/ -x^3 +9x^2 -27x+27= - (x^3 -9x^2+27x-27) = - (x-3)^3
3/ 8x^6 +36x^4y+54^2y^2+27y^3 = (2x^2+3y)^3
4/ x^3 - 6x^2y+12xy^2 -8y^3= (x-2y)^3
PH
1
17 tháng 10 2016
a) \(9\left(a+b\right)^2-4\left(a-2b\right)^2\)
\(=\left(3a+3b\right)^2-\left(2a-4b\right)^2\)
\(=\left(3a+3b-2a+4b\right)\left(3a+3b+2a-4b\right)\)
\(=\left(a+7b\right)\left(5a-b\right)\)
b) \(9x^6-12x^7+4x^8\)
\(=x^6\left(9-12x+4x^2\right)\)
\(=x^6\left(2x-3\right)^2\)
c) \(8x^6-27y^3\)
\(=\left(2x^2\right)^3-\left(3y\right)^3\)
\(=\left(2x^2-3y\right)\left(4x^4+6x^2y+9y^2\right)\)
d) \(\frac{1}{64}x^6-125y^3\)
\(=\left(\frac{1}{4}x^2\right)^3-\left(5y\right)^3\)
\(=\left(\frac{1}{4}x^2-5y\right)\left(\frac{1}{16}x^4+\frac{5}{6}xy+25y^2\right)\)
HP
24 tháng 9 2021
a. x2 + 6x + 9 = (x + 3)2
b. 25 + 10x + x2 = (5 + x)2
c. x2 + 8x + 16 = (x + 4)2
d. x2 + 14x + 49 = (x + 7)2
e. 4x2 + 12x + 9 = (2x + 3)2
f. 9x2 + 12x + 4 = (3x + 2)2
h. 16x2 + 8 + 1 = (4x + 1)2
i. 4x2 + 12xy + 9y2 = (2x + 3y)2
k. 25x2 + 20xy + 4y2 = (5x + 2y)2
24 tháng 9 2021
a) \(=\left(x+3\right)^2\)
b) \(=\left(x+5\right)^2\)
c) \(=\left(x+4\right)^2\)
d) \(=\left(x+7\right)^2\)
e) \(=\left(2x+3\right)^2\)
f) \(=\left(3x+2\right)^2\)
h) \(=\left(4x+1\right)^2\)
i) \(=\left(2x+3y\right)^2\)
k) \(=\left(5x+2y\right)^2\)
HL
3 tháng 7 2017
a) \(-y^2+\dfrac{1}{9}\)
= \(-\left(y^2-\dfrac{1}{9}\right)\)
= \(-\left(y-\dfrac{1}{3}\right)\left(y+\dfrac{1}{3}\right)\)
b) \(4\left(x-3\right)^2-9\left(x+1\right)^2\)
= \(\left(2x-3\right)^2-\left(3x+3\right)^2\)
= \(\left(2x-3+3x+3\right)\left(2x-3-3x-3\right)\)
= \(5x\left(-x-6\right)\)
c) \(25x^2-20xy+4y^2\)
= \(\left(5x-2y\right)^2\)
d) \(-9x^2+12xy-4y^2\)
= \(-\left(9x^2-12xy+4y^2\right)\)
= \(-\left(3x-2y\right)^2\)
e) \(25x^2-\dfrac{1}{8}x^2y^2\)
= \(\left(5x-\dfrac{\sqrt{2}}{4}xy\right)\left(5x+\dfrac{\sqrt{2}}{4}xy\right)\)
f) \(9x^2+6x+1\)
= \(\left(3x+1\right)^2\)
TN
3 tháng 7 2017
okey! Vì you t sẽ chăm thêm 1 lần nữa!!!^^
\(a.-y^2+\dfrac{1}{9}=\left(\dfrac{1}{3}\right)^2-y^2=\left(\dfrac{1}{3}-y\right)\left(\dfrac{1}{3}+y\right)\)
\(b,4\left(x-3\right)^2-9\left(x+1\right)^2=\left[2\left(x-3\right)\right]^2-\left[3\left(x+1\right)\right]^2=\left(2x-6\right)^2-\left(3x+3\right)^2=\left(2x-6-3x-3\right)\left(2x-6+3x+3\right)=\left(-x-9\right)\left(5x-3\right)\)\(c,25x^2-20xy+4y^2=\left(5x-2y\right)^2\)
\(d,-9x^2+12xy-4y^2=-\left(3x-2y\right)^2\)
\(e,25x^2-\dfrac{1}{8}x^2y^2=\left(5x-\dfrac{\sqrt{2}}{4}xy\right)\left(5x+\dfrac{\sqrt{2}}{4}xy\right)\)\(f,9x^2+6x+1=\left(3x+1\right)^2\)
b: \(\left(a-b\right)^2-c^2=\left(a-b-c\right)\left(a-b+c\right)\)
c: \(4x^2+12x+9=\left(2x+3\right)^2\)
d: \(25x^2-20xy+4y^2=\left(5x-2y\right)^2\)
e: \(8x^6-27y^3=\left(2x^2-3y\right)\left(4x^2+6x^2y+9y^2\right)\)