Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
x8+x7+1=x8+x7+x6-x6-x5-x4+x5+x4+x3-x3-x2-x+x2+x+1=x6(x2+x+1)-x4(x2+x+1)+x3(x2+x+1)-x(x2+x+1)+(x2+x+1)=(x2 +x+1)(x6-x4+x3-x)
Câu 1: 1. x.(x+y) = x2+xy
2. x4 : x2 = x2
3. x2y : xy = x
4. (x2+xy) : x
= x.(x+y) : x
= x+y
Câu 2: 1. 5x-10y=5.(x-2y)
2. x2-y2 = (x-y).(x+y)
3. x2+2xy+y2 = (x+y)2
4. x.(x-y)+2.(x-y)=(x-y).(x+2)
Câu 3: 1. 3x-9=0
=> 3.(x-3)=0
=> x-3=0
=> x=3
2. x2+2x+1=0
=> (x+1)2=0
=> x+1=0
=> x=-1
a) 3x2 - 5x - 3y2 + 5y
= 3(x2- y2) -5(x-y)
=3(x+y)(x-y) - 5(x-y)
=(x-y)(3x+3y-5)
b) 49 - x2+2xy-y2
= 72 - (x-y)2
=(7-x+y)(7+x-y)
a) \(3x^2-5x-3y^2+5y\)
\(=\left(3x^2-3y^2\right)-\left(5x-5y\right)\)
\(=3\left(x^2-y^2\right)-5\left(x-y\right)\)
\(=3\left[\left(x-y\right).\left(x+y\right)\right]-5\left(x-y\right)\)
\(3\left(x-y\right).\left(x+y\right)-5\left(x-y\right)\)
\(=\left(x-y\right).\left[3.\left(x+y\right)-5\right]\)
\(=\left(x-y\right)\left(3x+3y-5\right)\)
b) \(49-x^2+2xy-y^2\)
\(=7^2-x^2+2xy-y^2\)
\(=7^2-\left(x^2-2xy+y^2\right)\)
\(=7-\left(x-y\right)^2\)
\(=\sqrt{7}^2-\left(x-y\right)^2\)
\(=\left[7-\left(x-y\right).-7+\left(x-y\right)\right]\)
\(=\left(7-x+y\right).\left(-7+x-y\right)\)
\(\text{a)}x^3-6x^2+12x-8\)
\(=x^3-2x^2-4x^2+8x+4x-8\)
\(=\left(x^3-2x^2\right)-\left(4x^2-8x\right)+\left(4x-8\right)\)
\(=x^2\left(x-2\right)+4x\left(x-2\right)+4\left(x-2\right)\)
\(=\left(x-2\right)\left(x^2+4x+4\right)\)
\(=\left(x-2\right)\left(x+2\right)^2\)
\(\text{b)}8x^2+12x^2y+6xy^2+y^3=\left(2x+y\right)^3\)
Bài 2:
\(\text{a) }x^7+1=\left(x^{\frac{7}{3}}\right)^3+1^3=\left(x^{\frac{7}{3}}+1\right)\left[\left(x^{\frac{7}{3}}\right)^2-x^{\frac{7}{3}}+1\right]=\left(x^{\frac{7}{3}}+1\right)\left(x^{\frac{14}{3}}-x^{\frac{7}{3}}+1\right)\)
\(\text{b) }x^{10}-1=\left(x^5\right)^2-1^2=\left(x^5-1\right)\left(x^5+1\right)\)
Bài 3:
\(\text{a) }69^2-31^2=\left(69-31\right)\left(69+31\right)=38.100=3800\)
\(\text{b) }1023^2-23^2=\left(1023-23\right)\left(1023+23\right)=1000.1046=1046000\)
Bài 2:
a) \(x^2-y^2+3x-3y=\left(x^2-y^2\right)+\left(3x-3y\right)\)
\(=\left(x-y\right)\left(x+y\right)+3\left(x-y\right)=\left(x-y\right)\left(x+y+3\right)\)
b) \(5x-5y+x^2-2xy+y^2=\left(5x-5y\right)+\left(x^2-2xy+y^2\right)\)
\(=5\left(x-y\right)+\left(x-y\right)^2=\left(x-y\right)\left(x-y+5\right)\)
c) \(x^2-5x+4=x^2-x-4x+4=\left(x^2-x\right)-\left(4x-4\right)\)
\(=x\left(x-1\right)-4\left(x-1\right)=\left(x-1\right)\left(x-4\right)\)
b)\(x^2-2xy+y^2-z^2\)
\(=\left(x-y\right)^2-z^2\)
\(=\left(x-y-z\right)\left(x-y+z\right)\)
a) \(x^2-x-y^2-y\)
\(=\left(x^2-y^2\right)-\left(x+y\right)\)
\(=\left(x-y\right)\left(x+y\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(x-y-1\right)\)