phân tích thành nhân tử
a) x^2 - 4x - 5
b) x^2 - 4xy + 4y^2 - 36
c) x^2 - 9x + 20
d) (9x^2 -36) - (3x- 6).(2x+5)
làm hết hộ nha thank
K
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Những câu hỏi liên quan
14 tháng 11 2021
Bài 1:
\(a,=3x\left(3xy+5y-1\right)\\ b,=\left(z-2\right)\left(3z-5\right)\\ c,=\left(x+2y\right)^2-4z^2=\left(x+2y+2z\right)\left(x+2y-2z\right)\\ d,=x^2-3x+5x-15=\left(x-3\right)\left(x+5\right)\)
Bài 2:
\(a,\Leftrightarrow x\left(x-4\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\\ b,\Leftrightarrow2x+2-4x^2-12x=9\\ \Leftrightarrow4x^2+10x+7=0\\ \Leftrightarrow4\left(x^2+\dfrac{5}{2}x+\dfrac{25}{16}\right)+\dfrac{3}{4}=0\\ \Leftrightarrow4\left(x+\dfrac{5}{6}\right)^2+\dfrac{3}{4}=0\left(vô.lí\right)\\ \Leftrightarrow x\in\varnothing\\ c,\Leftrightarrow x^2-12x+36=0\\ \Leftrightarrow\left(x-6\right)^2=0\\ \Leftrightarrow x=6\)
KV
20 tháng 10 2023
a) Xem lại đề
b) x³ - 4x²y + 4xy² - 9x
= x(x² - 4xy + 4y² - 9)
= x[(x² - 4xy + 4y² - 3²]
= x[(x - 2y)² - 3²]
= x(x - 2y - 3)(x - 2y + 3)
c) x³ - y³ + x - y
= (x³ - y³) + (x - y)
= (x - y)(x² + xy + y²) + (x - y)
= (x - y)(x² + xy + y² + 1)
d) 4x² - 4xy + 2x - y + y²
= (4x² - 4xy + y²) + (2x - y)
= (2x - y)² + (2x - y)
= (2x - y)(2x - y + 1)
e) 9x² - 3x + 2y - 4y²
= (9x² - 4y²) - (3x - 2y)
= (3x - 2y)(3x + 2y) - (3x - 2y)
= (3x - 2y)(3x + 2y - 1)
f) 3x² - 6xy + 3y² - 5x + 5y
= (3x² - 6xy + 3y²) - (5x - 5y)
= 3(x² - 2xy + y²) - 5(x - y)
= 3(x - y)² - 5(x - y)
= (x - y)[(3(x - y) - 5]
= (x - y)(3x - 3y - 5)
LD
4 tháng 11 2021
a) \(x-xy+y-y^2=x\left(1-y\right)+y\left(1-y\right)=\left(x+y\right)\left(1-y\right)\)
b) \(x^2-2x-y^2+1=\left(x^2-2x+1\right)-y^2=\left(x-1\right)^2-y^2=\left(x-y-1\right)\left(x+y-1\right)\)
c) \(4x^2-4xy+y^2=\left(2x\right)^2-2.2x.y+y^2=\left(2x-y\right)^2\)
d) \(9x^3-9x^2y-4x+4y=9x^2\left(x-y\right)-4\left(x-y\right)=\left(9x^2-4\right)\left(x-y\right)=\left(3x-2\right)\left(3x+2\right)\left(x-y\right)\)
e) \(x^3+2+3\left(x^3-2\right)=x^3+2+3x^3-6=4x^3-4=4\left(x^3-1\right)=4\left(x-1\right)\left(x^2+x+1\right)\)
ML
6 tháng 8 2015
a)x3-6x2+9x=x(x2-6x+9)=x(x-3)2
b)x2-2x-4y2-4y=(x2-2x+1)-(4y2+4y+1)=(x-1)2-(2y+1)2=(x-1-2y-1)(x-1+2y+1)=(x-2y-2)(x+2y)
c)x2-x+xy-y=x(x-1)+y(x-1)=(x-1)(x+y)
d)3x2-6xy-75+3y2=3[(x2-2xy+y2)-25]=3[(x-y)2-52]=3(x-y-5)(x-y+5)
e)2x2-5x-7=(2x2+2x)-(7x+7)=2x(x+1)-7(x+1)=(x+1)(2x-7)
f)x4+36=x4+12x2+36-12x2=(x2+6)2-12x2=(x2-\(\sqrt{12}x\)+6)(x2+\(\sqrt{12}x\)+6)
h)x4+4y4=x4+4x2y2+4y2-4x2y2=(x2+2y2)-4x2y2=(x2+2y2-2xy)(x2+2y2+2xy)
KN
11 tháng 10 2019
a) \(4x^2-4xy+y^2-9\)
\(=\left(2x-y\right)^2-3^2\)
\(=\left(2x-y+3\right)\left(2x-y-3\right)\)
b) \(x^2-36+4xy+4y^2\)
\(=\left(4y^2+4xy+x^2\right)-36\)
\(=\left(2y+x\right)^2-6^2\)
\(=\left(2y+x+6\right)\left(2y+x-6\right)\)
c) \(9x^2-12xy-25+4y^2\)
\(=\left(9x^2-12xy+4y^2\right)-25\)
\(=\left(3x-2y\right)^2-5^2\)
\(=\left(3x-2y+5\right)\left(3x-2y-5\right)\)
d) \(25x^2+10x-4y^2+1\)
\(=\left(25x^2+10x+1\right)-4y^2\)
\(=\left(5x+1\right)^2-\left(2y\right)^2\)
\(=\left(5x+2y+1\right)\left(5x-2y+1\right)\)
1 tháng 7 2016
1.\(x^2-2x-4y^2-4y=\left(x+2y\right)\left(x-2y\right)-2\left(x+2y\right)=\left(x+2y\right)\left(x-2y-2\right)\)
2.\(x^4+2x^3-4x-4=\left(x^2+2\right)\left(x^2-2\right)+2x\left(x^2-2\right)=\left(x^2-2\right)\left(x^2+2x-2\right)\)
3.\(3x^2-3y^2-2\left(x-y\right)^2=3\left(x-y\right)\left(x+y\right)-2\left(x-y\right)\left(x-y\right)=\left(x-y\right)\left(3x+3y-2x+2y\right)\)\(=\left(x-y\right)\left(x+5y\right)\)
4.\(x^3-4x^2-9x+36=x^2\left(x-4\right)-9\left(x-4\right)=\left(x-3\right)\left(x+3\right)\left(x-4\right)\)
5.\(\left(x-1\right)\left(2x+1\right)+3\left(x-1\right)\left(x+2\right)\left(2x+1\right)=\left(x-1\right)\left(2x+1\right)\left(1+3x+6\right)\)\(=\left(x-1\right)\left(2x+1\right)\left(3x+7\right)\)
6.\(\left(6x+3\right)-\left(2x-5\right)\left(2x+1\right)=3\left(2x+1\right)-\left(2x-5\right)\left(2x+1\right)\)\(=\left(2x+1\right)\left(3-2x-5\right)=\left(2x+1\right)\left(-2-2x\right)=-2\left(2x+1\right)\left(x+1\right)\)
7.\(\left(x-5\right)^2+\left(x+5\right)\left(x-5\right)+\left(x-5\right)\left(2x+1\right)=\left(x-5\right)\left(x-5+x+5+2x+1\right)\)\(=\left(x-5\right)\left(4x+1\right)\)
8.\(\left(3x-2\right)\left(4x-3\right)+\left(3x-2\right)\left(x-1\right)-2\left(3x-2\right)\left(x+1\right)\)\(=\left(3x-2\right)\left(4x-3+x-1-2x-2\right)=\left(3x-2\right)\left(3x-6\right)=3\left(3x-2\right)\left(x-2\right)\)
PN
15 tháng 11 2015
a. \(\left(x^2+2x\right)^2+9x^2+18x+20=x^4+4x^3+13x^2+18x+20\)
\(=x^4+2x^3+2x^3+5x^2+4x^2+4x^2+8x+10x+20\)
\(=x^2\left(x^2+2x+5\right)+2x\left(x^2+2x+5\right)+4\left(x^2+2x+5\right)=\left(x^2+2x+5\right)\left(x^2+2x+4\right)\)
Lưu ý: có thể dùng phương pháp đồng nhất hệ số dưới dạng \(\left(x^2+ax+5\right)\left(x^2+bx+4\right)\) khi thực xong bước 1
b. \(x^3+2x-3=x^3+x^2-x^2+3x-x-3=x\left(x^2+x+3\right)-\left(x^2+x+3\right)=\left(x-1\right)\left(x^2+x+3\right)\)
c. \(x^2-4xy+4y^2-2x+4y-35=\left(x-2y\right)^2-2\left(x-2y\right)+1-36=\left(x-2y-1\right)^2-6^2\)
\(=\left(x-2y-1-6\right)\left(x-2y-1+6\right)=\left(x-2y-7\right)\left(x-2y+5\right)\)
T
26 tháng 8 2023
\(4x^2-4xy+y^2\)
\(=\left(2x\right)^2-2\cdot2x\cdot y+y^2\)
\(=\left(2x-y\right)^2\)
\(---\)
\(\left(x+1\right)^2-9y^2\)
\(=\left(x+1\right)^2-\left(3y\right)^2\)
\(=\left(x+1-3y\right)\left(x+1+3y\right)\)
\(=\left(x-3y+1\right)\left(x+3y+1\right)\)
\(---\)
\(2x+5^2-9x^2\) (kt lại đề bài)
\(2x-1^2-3x-1^2\)
\(=-x-2=-1\cdot\left(x+2\right)\)
a, \(x^2-4x-5\)
\(=x^2-5x+x-5=x\left(x-5\right)+\left(x-5\right)\)
\(=\left(x+1\right)\left(x-5\right)\)
b, \(x^2-4xy+4y^2-36\)
\(=\left(x-2y\right)^2-36=\left(x-2y-6\right)\left(x-2y+6\right)\)
c, \(x^2-9x+20=x^2-5x-4x+20\)
\(=x\left(x-5\right)-4\left(x-5\right)\)
\(=\left(x-4\right)\left(x-5\right)\)
d, \(\left(9x^2-36\right)-\left(3x-6\right)\left(2x+5\right)\)
\(=\left(3x-6\right)\left(3x+6\right)-\left(3x-6\right)\left(2x+5\right)\)
\(=\left(3x-6\right)\left(3x+6-2x-5\right)\)
\(=3\left(x-2\right)\left(x+1\right)\)
a) \(x^2-4x-5=x^2-4x+4-9\)
= \(\left(x-2\right)^2-3^2\)
= \(\left(x-2-3\right)\left(x-2+3\right)=\left(x-5\right)\left(x+1\right)\)
b) \(x^2-4xy+4y^2-36\)
= \(\left(x-2y\right)^2-6^2=\left(x-2y-6\right)\left(x-2y+6\right)\)
c) \(x^2-9x+20\)
= \(\left(x-5\right)\left(x-4\right)\)
d) \(\left(9x^2-36\right)-\left(3x-6\right)\left(2x+5\right)\)
= \(\left(3x-6\right)\left(3x+6\right)-\left(3x-6\right)\left(2x+5\right)\)
= \(\left(3x-6\right)\left(3x+6-2x-5\right)=\left(3x-6\right)\left(x+1\right)\)