4-x2+4xy-4y2
Biểu thức nào dưới đây là bình phương của hiệu x - 2y:
A. x2 + 2xy + 4y2.
B. x2 – 2xy + 4y2 .
C. x2 – 4xy + 4y2 .
D. x2 + 4xy + 4y2
x2 + 4y2 - 4xy - 4
\(x^2+4y^2-4xy-4\)
\(=\left(x^2-4xy+4y^2\right)-4\)
\(=\left(x-2y\right)^2-2^2\)
\(=\left(x-2y-2\right)\left(x-2y+2\right)\)
Tính giá trị biểu thức N = (x 2 − 4y 2 )(x − 2y) x 2 − 4xy + 4y 2 tại x = -9998 và y = -1.
A. N = -9996
B. N = 10000
C. N = -10000
D. N = -19997
x2+4xy-9+4y2
\(x^2+4xy-9+4y^2\)
\(=\left(x^2+4xy+4y^2\right)-9\)
\(=\left(x+2y\right)^2-3^2\)
\(=\left(x+2y+3\right)\left(x+2y-3\right)\)
\(=\left(x+2y\right)^2-9=\left(x+2y-3\right)\left(x+2y+3\right)\)
x2+4xy-4z2+4y2
= x^2+4xy+4y^2 -4z^2
= (x+2y)^2 -4z^2
=(x+2y-2z)(x+2y+2z)
\(=\left(x+2y-2z\right)\left(x+2y+2z\right)\)
=x2+4xy+4y2-4z2
=(x+2y)2-4z2
=(x+2y-4z)(x+2y+4z)
chắc chắn đúng
x2 + 4xy + 4y2 - 9
Đề bài yêu cầu gì thế em?
`x^2 +4xy+ 4y^2 -9`
`= (x^2 + 2x.2y + 4y^2) -9`
`= (x+2y)^2 - 3^2`
`= (x+2y -3)(x+2y +3)`
x2 + 4xy + 4y2 - 9
= (x2 + 4xy + 4y2)-32
= (x+2y)2 - 32
= (x+2y-3).(x+2y+3)
a, x2 + 4xy - 4z2 + 4y2 b,x2 + 2x - 15
\(x^2+4xy-4z^2+4y^2\)
\(=x^2+4xy+4y^2-4z^2\)
\(=\left(x+2y\right)^2-4z^2\)
\(=\left(x+2y-2z\right)\left(x+2y+2z\right)\)
\(x^2+2x-15\)
\(=x^2+2x+1-16\)
\(=\left(x+1\right)^2-16\)
\(=\left(x+1-4\right)\left(x+1+4\right)\)
\(=\left(x-3\right)\left(x+5\right)\)
Phân tích đa thức thành nhân tử
1, a6 + b3
2, x2 – 10x + 25
3, 8x3 – \(\dfrac{1}{8}\)
4, x2 + 4xy + 4y2
1, \(a^6+b^3=\left(a^2+b\right)\left(a^4-a^2b+b^2\right)\)
2, \(x^2-10x+25=\left(x-5\right)^2\)
3, \(8x^3-\dfrac{1}{8}=\left(2x-\dfrac{1}{2}\right)\left(4x^2+x+\dfrac{1}{4}\right)\)
4, \(x^2+4xy+4y^2=\left(x+2y\right)^2\)
1) \(a^6+b^3=\left(a^2\right)^3+b^3=\left(a^2+b\right)\left(a^4-a^2b+b^2\right)\)
2) \(x^2-10x+25=\left(x-5\right)^2\)
3) \(8x^3-\dfrac{1}{8}=\left(2x\right)^3-\left(\dfrac{1}{3}\right)^3=\left(2x-\dfrac{1}{3}\right)\left(4x^2+\dfrac{2x}{3}+\dfrac{1}{4}\right)\)
4) \(x^2+4xy+4y^2=\left(x+2y\right)^2\)
1: \(a^6+b^3=\left(a^2+b\right)\left(a^4-a^2b+b^2\right)\)
2: \(x^2-10x+25=\left(x-5\right)^2\)
3: \(8x^3-\dfrac{1}{8}=\left(2x-\dfrac{1}{2}\right)\left(4x^2+x+\dfrac{1}{4}\right)\)
4: \(x^2+4xy+4y^2=\left(x+2y\right)^2\)
Tính nhanh giá trị của biểu thức: M = x2 + 4y2 – 4xy tại x = 18 và y = 4
M = x2 + 4y2 – 4xy
= x2 – 2.x.2y + (2y)2 (Hằng đẳng thức (2))
= (x – 2y)2
Thay x = 18, y = 4 ta được:
M = (18 – 2.4)2 = 102 = 100
a, 2x2 - 4xy + 2y2
b, x2 + 4xy + 4y2 - 9
c, x4 - x3y + x - y
\(2x^2-4xy+2y^2\\ =2\left(x^2-2xy+y^2\right)\\ =2\left(x-y\right)^2\)
a) 2x2-4xy+2y2
= 2x2-2xy-2xy+2y2
= 2x(x-y)-2y(x-y)
= (2x-2y)(x-y)
b) x2+4xy+4y2-9
= (x+2y)2-32
= (x+2y-3)(x+2y+3)
c) x4-x3y+x-y
= x3(x-y)+(x-y)
= (x3+1)(x-y)
\(a,=2\left(x^2-2xy+y^2\right)=2\left(x-y\right)^2\\ b,=\left(x+2y\right)^2-9=\left(x+2y-3\right)\left(x+2y+3\right)\\ c,=x^3\left(x-y\right)+\left(x-y\right)\\ =\left(x+1\right)\left(x-y\right)\left(x^2-x+1\right)\)