1/ Phân tích đa thức thành nhân tử:
a) x2- y2- 2yz-z2
b) 2xy-x2 -y2+ 16
b
c) 3a2- 6ab+ 3b2- 12c2
2/ Tính nhanh:
a) 37,5.8,5-7,5.3.4+6,6.7,5+1,5.37,5
b) 352+402-252+80.35
HELP MEEEE!!!!!
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Những câu hỏi liên quan
ND
Nguyễn Đức Trí
VIP
8 tháng 9 2023
a) \(x^2-y^2-3x+3y\)
\(=\left(x-y\right)\left(x+y\right)-3\left(x-y\right)\)
\(=\left(x-y\right)\left(x+y-3\right)\)
b) \(2x+2y-x^2+y^2\)
\(=2\left(x+y\right)-\left(x^2-y^2\right)\)
\(=2\left(x+y\right)-\left(x-y\right)\left(x+y\right)\)
\(=\left(x+y\right)\left(2-x+y\right)\)
c) \(x^2-16+y^2+2xy\)
\(=x^2+y^2+2xy-16\)
\(=\left(x+y\right)^2-16\)
\(=\left(x+y+4\right)\left(x+y-4\right)\)
NX
8 tháng 9 2023
a) \(x^2-y^2-3x+3y\)
\(=\left(ax+y\right)\left(ax-y\right)-3.\left(x-y\right)\)
b) \(2x+2y-x^2+y^2\)
\(=2\left(x+y\right)-\left(x+y\right)\left(x-y\right)\)
c) \(x^2-16+y^2+2xy\)
\(=\left(x+y\right)\left(x-y\right)+2xy-16\)
MH
25 tháng 10 2021
a) \(3x\left(2x-y\right)+5y\left(y-2x\right)\)
\(=3x\left(2x-y\right)-5y\left(2x-y\right)\)
\(=\left(3x-5y\right)\left(2x-y\right)\)
b) \(\left(x-5\right)^2-9\left(x+y\right)^2\)
\(=\left(x-5\right)^2-3^2\left(x+y\right)^2\)
\(=\left(x-5\right)^2-\left(3x+3y\right)^2\)
\(=\left(x-5+3x+3y\right)\left(x-5-3x-3y\right)\)
\(=\left(4x+3y-5\right)\left(-2x-3y-5\right)\)
25 tháng 10 2021
a: \(3x\left(2x-y\right)+5y\left(y-2x\right)=\left(2x-y\right)\left(3x-5y\right)\)
e: \(x^2-10x+24=\left(x-4\right)\left(x-6\right)\)
VH
2
HN
27 tháng 9 2017
\(a)37,5.8,5-7,5.3,4-6,6.7,5+1,5.37,5\)
\(=\left(37,5.8,5+1,5.37,5\right)-\left(7,5.3,4+6,6.7,5\right)\)
\(=37,5\left(8,5+1,5\right)-7,5\left(3,4+6,6\right)\)
\(=37,5.10-7,5.10\)
\(=10\left(37,5-7,5\right)\)
\(=10.30\)
\(=300\)
\(b)35^2+40^2-25^2+80.35\)
\(=\left(35^2+80.35+40^2\right)-25^2\)
\(=\left(35+40\right)^2-25^2\)
\(=75^2-25^2\)
\(=\left(75-25\right)\left(75+25\right)\)
\(=50.100\)
\(=5000.\)
1 tháng 11 2021
\(1,\\ a,=\left(x-y\right)^2-z^2=\left(x-y-z\right)\left(x-y+z\right)\\ b,=a^2\left(a-x\right)-y\left(a-x\right)=\left(a^2-y\right)\left(a-x\right)\\ c,=\left(x-y\right)^2-z\left(x-y\right)=\left(x-y\right)\left(x-y-z\right)\\ d,=x\left(x-2y\right)+t\left(x-2y\right)=\left(x+t\right)\left(x-2y\right)\\ 2,\\ \Rightarrow x^2-4x+4-x^2+9=6\\ \Rightarrow-4x=-7\Rightarrow x=\dfrac{7}{4}\\ 3,\\ a,x^2+2x+2=\left(x+1\right)^2+1\ge1>0\\ b,-x^2+4x-5=-\left(x-2\right)^2-1\le-1< 0\)
PT
1
PA
1
AN
27 tháng 9 2017
a)\(37,5\times8,5+-7,5\times3,4-6,6\times7,5+1,5\times37,5\)
\(=\left(37,5\times8,5+1,5\times37,5\right)-\left(7,5\times3,4+6,6\times7,5\right)\)
\(=37,5\left(8,5+1,5\right)-7,5\left(3,4+6,6\right)\)
\(=375-75\)
\(=300\)
2 tháng 10 2018
a) 2x^2 - 2xy - 5x +5y
= (2x^2 - 2xy ) - ( 5x- 5 y)
=2x(x-y) - 5(x-y)
=(x- y). (2x- 5)
b)8x2 +4xy-2ax-ay
=(8x2 +4xy) -(2ax+ay)
=4x(2x+y)-a(2x+y)
=(2x+y).(4x-a)
c)=x(x2 -4x +4)
=x(x-2)2
d)=16- (x2 -2xy +y^2)
=4^2-(x-y)^2
=(4-x+y).(4+x-y)
các câu còn lại tg tự
chúc bn hok tốt
27 tháng 10 2021
\(a,=\left(x-y\right)\left(x+y\right)-\left(x+y\right)=\left(x+y\right)\left(x-y-1\right)\\ b,=\left(x+y\right)\left(x-5\right)\\ c,=5x^2\left(x-y\right)-10x\left(x-y\right)=5x\left(x-2y\right)\left(x-y\right)\\ d,=x^2-2xy=x\left(x-2y\right)\\ e,=\left(3x-2y\right)\left(9x^2+6xy+4y^2\right)\)
27 tháng 9 2017
\(a,2x^2-2xt-5x+5y\)
\(=\left(2x^2-5x\right)-\left(2xy-5y\right)\)
\(=x\left(2x-5\right)-y\left(2x-5\right)\)
\(=\left(2x-5\right)\left(x-y\right)\)
\(b,8x^2+4xy-2ax-ay\)
\(=\left(8x^2-2ax\right)+\left(4xy-ay\right)\)
\(=2x\left(4x-a\right)+y\left(4x-a\right)\)
\(=\left(4x-a\right)\left(2x+y\right)\)
\(c,x^3-4x^2+4x\)
\(=x^3-2x^2-2x^2+4x\)
\(=\left(x^3-2x^2\right)-\left(2x^2-4x\right)\)
\(=x^2\left(x-2\right)-2x\left(x-2\right)\)
\(=\left(x-2\right)\left(x^2-2x\right)=x\left(x-2\right)\left(x-2\right)\)
\(=x\left(x-2\right)^2\)
\(d,2xy-x^2-y^2+16\)
\(=-\left(x^2-2xy+y^2-16\right)\)
\(=-\left[\left(x-y\right)^2-4^2\right]\)
\(=-\left(x-y-4\right)\left(x-y+4\right)\)
\(e,x^2-y^2-2yz-z^2\)
\(=x^2-\left(y^2+2yz+z^2\right)\)
\(=x^2-\left(y+z\right)^2=\left(x-y-z\right)\left(x+y+z\right)\)
Bài 1:
a) \(x^2-y^2-2yz-z^2\)
\(=x^2-\left(y^2+2yz+z^2\right)\)
\(=x^2-\left(y+z\right)^2\)
\(=\left(x+y+z\right)\left(x-y-z\right)\)
b) \(2xy-x^2-y^2+16\)
\(=16-\left(x^2-2xy+y^2\right)\)
\(=4^2-\left(x-y\right)^2\)
\(=\left(4+x-y\right)\left(4-x+y\right)\)
c) \(3a^2-6ab+3b^2-12c^2\)
\(=3\left(a^2-2ab+b^2-4c^2\right)\)
\(=3\left[\left(a^2-2ab+b^2\right)-\left(2c\right)^2\right]\)
\(=3\left[\left(a-b\right)^2-\left(2c\right)^2\right]\)
\(=3\left(a-b-2c\right)\left(a-b+2c\right)\)
Bài 2:
a) \(37,5\cdot8,5-7,5\cdot3,4+6,6\cdot7,5+1,5\cdot37,5\)
\(=\left(37,5\cdot8,5+1,5\cdot37,5\right)-\left(7,5\cdot3,4-6,6\cdot7,5\right)\)
\(=37,5\cdot\left(8,5+1,5\right)-7,5\cdot\left(3,4-6,6\right)\)
\(=37,5\cdot10-7,5\cdot10\) (mk đoán đề bạn chép sai)
\(=10\cdot\left(37,5-7,5\right)\)
\(=10\cdot30\)
\(=300\)
b) \(35^2+40^2-25^2+80\cdot35\)
\(=\left(40^2+2\cdot40\cdot35+35^2\right)-25^2\)
\(=\left(40+35\right)^2-25^2\)
\(=75^2-25^2\)
\(=\left(75+25\right)\left(75-25\right)\)
\(=100\cdot50\)
\(=5000\)
Bài 1:
a, \(x^2-y^2-2yz-z^2=x^2-\left(y^2+2yz+z^2\right)\)
\(=x^2-\left(y+z\right)^2=\left(x-y-z\right)\left(x+y+z\right)\)
b, \(2xy-x^2-y^2+16=16-\left(x^2-2xy+y^2\right)\)
\(=16-\left(x-y\right)^2=\left(4-x+y\right)\left(4+x-y\right)\)
c, \(3a^2-6ab+3b^2-12c^2\)
\(=3\left(a-b\right)^2-12c^2=3\left[\left(a-b\right)^2-4c^2\right]\)
\(=3\left(a-b+2c\right)\left(a-b-2c\right)\)
Bài 2:
a, \(37,5.8,5-7,5.3,4+6,6.7,5+1,5.37,5\)
\(=37,5.\left(8,5+1,5\right)-7,5.\left(3,4+6,6\right)\)
\(=37,5.10-7,5.10=10.\left(37,5-7,5\right)\)
\(=10.30=300\)
b, \(35^2+40^2-25^2+80.35\)
\(=\left(40^2+2.40.35+35^2\right)-25^2\)
\(=\left(40+35\right)^2-25^2=75^2-25^2\)
\(=\left(75-25\right)\left(75+25\right)=50.100=5000\)