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N
1
8 tháng 12 2016
(x+5)2+(x-2)2-4(x-3)(x+3)
=x2+10x+25+x2-4x+4-4x2+36
=x2+x2-4x2+10x-4x+25+4+36
=-2x2+6x+65
NT
2
12 tháng 3 2020
\(\frac{6}{x^2-9}+\frac{5x}{x-3}+\frac{x}{x+3}\)
\(=\frac{6x}{\left(x-3\right)\left(x+3\right)}+\frac{5x}{x-3}+\frac{x}{x+3}\)
\(=\frac{6x}{\left(x-3\right)\left(x+3\right)}-\frac{5x\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}+\frac{x\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}\)
\(=\frac{6x+5x\left(x+3\right)+x\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}\)
\(=\frac{6x\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}=\frac{6x}{x-3}\)
12 tháng 3 2020
\(\frac{6x}{x^2-9}+\frac{5x}{x-3}+\frac{x}{x+3}\left(x\ne\pm3\right)\)
\(=\frac{6x}{\left(x-3\right)\left(x+3\right)}+\frac{5x\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}+\frac{x\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}\)
\(=\frac{6x+5x^2+15x+x^2-3x}{\left(x-3\right)\left(x+3\right)}\)
\(=\frac{6x^2+18x}{\left(x-3\right)\left(x+3\right)}=\frac{6x\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}=\frac{6x}{x-3}\)
LT
3
6 tháng 8 2020
\(\frac{4}{x-3}+\frac{5}{x+3}-\frac{13-9x^2}{x^2-9}\)
ĐKXĐ : \(x\ne\pm3\)
\(=\frac{4}{x-3}+\frac{5}{x+3}-\frac{13-9x^2}{\left(x+3\right)\left(x-3\right)}\)
\(=\frac{4\left(x+3\right)}{\left(x+3\right)\left(x-3\right)}+\frac{5\left(x-3\right)}{\left(x+3\right)\left(x-3\right)}-\frac{13-9x^2}{\left(x+3\right)\left(x-3\right)}\)
\(=\frac{4x+12}{\left(x+3\right)\left(x-3\right)}+\frac{5x-15}{\left(x+3\right)\left(x-3\right)}-\frac{13-9x^2}{\left(x+3\right)\left(x-3\right)}\)
\(=\frac{4x+12+5x-15-13+9x^2}{\left(x+3\right)\left(x-3\right)}\)
\(=\frac{9x^2+9x-16}{\left(x+3\right)\left(x-3\right)}=\frac{9x^2+9x-16}{x^2-9}\)
LT
3
DH
Đỗ Hoàn
CTVHS
VIP
18 giờ trước (10:40)
\((x+4)(x-2)-(x-3)^2\)
\(=(x⋅x+x⋅(−2)+4⋅x+4⋅(−2))−(x⋅x+x⋅(−3)+(−3)⋅x+(−3)⋅(−3))\)
\(=(x^2-2x+4x-8)-(x^2-3x-3x+9)\)
\(\) \(=(x^2+2x-8)-(x^2-6x+9)\)
\(=x^2+2x-8-x^2+6x-9\)
\(=8x−17\)
18 giờ trước (10:58)
(x+4)(x-2)-(x-3)^2
=x^2-2x+4x-8-x^2+6x-9
=2x-8-9
=2x-17
tichs ddi bn owi
VT
1
NN
1
AK
7 tháng 7 2018
\(\left(x+3\right)\left(x-2\right)\left(x+1\right)\)
\(=\left(x^2+3x-2x-6\right)\left(x+1\right)\)
\(=\left(x^2+x-6\right)\left(x+1\right)\)
\(=x^3+x^2-6x+x^2+x-6\)
\(=x^3+2x^2-5x-6\)
TH
1
27 tháng 7 2016
\(\left(x^2-9\right)^2-\left(x+3\right)\left(x-3\right)\left(x^2+9\right)=\left(x-3\right)^2\left(x+3\right)^2-\left(x+3\right)\left(x-3\right)\left(x^2+9\right)\)
\(=\left(x-3\right)\left(x+3\right)\left[\left(x-3\right)\left(x+3\right)-x^2+9\right]=\left(x-3\right)\left(x+3\right)\left[x^2-9-x^2-9\right]=\left(x-3\right)\left(x+3\right)\cdot\left(-18\right)\)
\(=-18\left(x+3\right)\left(x-3\right)\)
NQ
1
7 tháng 8 2017
3x(x+1)(x-1)-(2x-3)2 =3x(x2-1)-4x2+12x-9=3x3-3x-4x2+12x-9=3x3-4x2+9x-9
3(x+1)+(x+1)2=(x+1)(1+x+1)=(x+1)(x+2)=x2+2x+x+2=x2+3x+2
the end
giúp tui với mn ơi
\(=x^2-9-x^2=-9\)