Giải pt
l x^2 - 2xy + y^2 - 3x -2y -1 l + 4 = 2x + l x^2 - 3x + 2 l
K
Khách
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24 tháng 7 2018
a) \(3x^2-3y^2-x-y\)
\(\Leftrightarrow3\left(x^2-y^2\right)-x-y\)
\(\Leftrightarrow3\left(x-y\right)\left(x+y\right)-\left(x+y\right)\)
\(\Leftrightarrow3\left(x-y\right)\)
d) \(3x^2-7x+4\)
\(\Leftrightarrow3x^2-7x+7-3\)
\(\Leftrightarrow\left(3x^2-3\right)-\left(7x-7\right)\)
\(\Leftrightarrow3\left(x^2-1\right)-7\left(x-1\right)\)
\(\Leftrightarrow3\left(x-1\right)\left(x+1\right)-7\left(x-1\right)\)
\(\Leftrightarrow\left(x-1\right)\left(3\left(x+1\right)-7\right)\)
\(\Leftrightarrow\left(x+1\right)\left(3x-6\right)\)
e) \(-2x^2+3x-1\)
\(\Leftrightarrow\left(-2x^2-1^2\right)+3x\)
\(\Leftrightarrow\left(-2x-1\right)\left(-2x+1\right)+3x\)
f) \(x^2+2xy+y^2-2x-2y\)
\(\Leftrightarrow\left(x+y\right)^2-2\left(x+y\right)\)
\(\Leftrightarrow\left(x+y\right)^2-2\left(x+y\right)\)
k) \(2x^2+5x+3\)
\(\Leftrightarrow2x^2+2x+3x+3\)
\(\Leftrightarrow2x\left(x+1\right)+3\left(x+1\right)\)
\(\Leftrightarrow\left(2x+3\right)\left(x+1\right)\)
l) \(x^2-2x-y^2+1\)
\(\Leftrightarrow\left(x^2-2x+1\right)-y^2\)
\(\Leftrightarrow\left(x-1\right)^2-y^2\)
\(\Leftrightarrow\left(x-1-y\right)\left(x-1+y\right)\)
24 tháng 7 2018
a) \(3x^2-3y^2-x-y\)
\(\Leftrightarrow3\left(x^2-y^2\right)-x-y\)
\(\Leftrightarrow3\left(x-y\right)\left(x+y\right)-\left(x+y\right)\)
\(\Leftrightarrow3\left(x-y\right)\)
d) \(3x^2-7x+4\)
\(\Leftrightarrow3x^2-7x+7-3\)
\(\Leftrightarrow\left(3x^2-3\right)-\left(7x-7\right)\)
\(\Leftrightarrow3\left(x^2-1\right)-7\left(x-1\right)\)
\(\Leftrightarrow3\left(x-1\right)\left(x+1\right)-7\left(x-1\right)\)
\(\Leftrightarrow\left(x-1\right)\left(3\left(x+1\right)-7\right)\)
\(\Leftrightarrow\left(x+1\right)\left(3x-6\right)\)
e) \(-2x^2+3x-1\)
\(\Leftrightarrow\left(-2x^2-1^2\right)+3x\)
\(\Leftrightarrow\left(-2x-1\right)\left(-2x+1\right)+3x\)
f) \(x^2+2xy+y^2-2x-2y\)
\(\Leftrightarrow\left(x+y\right)^2-2\left(x+y\right)\)
\(\Leftrightarrow\left(x+y\right)^2-2\left(x+y\right)\)
k) \(2x^2+5x+3\)
\(\Leftrightarrow2x^2+2x+3x+3\)
\(\Leftrightarrow2x\left(x+1\right)+3\left(x+1\right)\)
\(\Leftrightarrow\left(2x+3\right)\left(x+1\right)\)
l) \(x^2-2x-y^2+1\)
\(\Leftrightarrow\left(x^2-2x+1\right)-y^2\)
\(\Leftrightarrow\left(x-1\right)^2-y^2\)
\(\Leftrightarrow\left(x-1-y\right)\left(x-1+y\right)\)
NK
3
28 tháng 5 2018
Phương trình đã cho tương đương
\(\Leftrightarrow\left|\left(x-y\right)^2+2\left(x-y\right)+1+x-2\right|+\left|x^2-3x+2\right|=2\left(x-2\right)\) (1)
Vế trái không âm => x \(\ge\)2
\(\Leftrightarrow\left|\left(x-y+1\right)^2+\left(x-2\right)\right|+\left|\left(x-2\right)\left(x-1\right)\right|=2\left(x-2\right)\)
\(\Leftrightarrow\left(x-y+1\right)^2+\left(x-2\right)+\left(x-2\right)\left(x-1\right)=2\left(x-2\right)\) \(\left(x\ge2\right)\)
\(\Leftrightarrow\left(x-y+1\right)^2+\left(x-2\right)^2=0\)
\(\Leftrightarrow\hept{\begin{cases}x-y+1=0\\x-2=0\end{cases}}\Leftrightarrow\hept{\begin{cases}x=2\\y=3\end{cases}}\)Thỏa mãn điều kiện \(\ge\)2
Vậy pt có nghiệm \(\hept{\begin{cases}x=2\\y=3\end{cases}}\)
TN
28 tháng 5 2018
mày thử thay x=2 với y=3 vào pt đi xem đúng ko :)) thằng óc lz ngu vclll :))
4 tháng 11 2018
a) \(2x^2-2y^2\)
\(=2\left(x^2-y^2\right)\)
\(=2\left(x-y\right)\left(x+y\right)\)
b) \(x^2-4x+4\)
\(=x^2-2\cdot x\cdot2+2^2\)
\(=\left(x-2\right)^2\)
c) \(x^2+2x+1-y^2\)
\(=\left(x+1\right)^2-y^2\)
\(=\left(x-y+1\right)\left(x+y+1\right)\)
d) \(x^2-4x\)
\(=x\left(x-4\right)\)
e) \(x^2+10x+25\)
\(=x^2+2\cdot x\cdot5+5^2\)
\(=\left(x+5\right)^2\)
g) \(x^2-2xy+y^2-9\)
\(=\left(x-y\right)^2-3^2\)
\(=\left(x-y-3\right)\left(x-y+3\right)\)
h) \(2x^2-2\)
\(=2\left(x^2-1\right)\)
\(=2\left(x-1\right)\left(x+1\right)\)
i) \(5x^2-5xy+9x-9y\)
\(=5x\left(x-y\right)+9\left(x-y\right)\)
\(=\left(x-y\right)\left(5x+9\right)\)
k) \(y^2-4y+4-x^2\)
\(=\left(y-2\right)^2-x^2\)
\(=\left(y-x-2\right)\left(y+x-2\right)\)
l) \(x^2-16\)
\(=x^2-4^2\)
\(=\left(x-4\right)\left(x+4\right)\)
m) \(3x^2-3xy+2x-2y\)
\(=3x\left(x-y\right)+2\left(x-y\right)\)
\(=\left(x-y\right)\left(3x+2\right)\)
o) \(3x^4-6x^3+3x^2\)
\(=3x^2\left(x^2-2x+1\right)\)
\(=3x^2\left(x-1\right)^2\)
PT
4 tháng 11 2018
a) 2x2 - 2y2
= (2x - 2y)(2x + 2y)
= 4(x - y)(x + y)
b) x2 - 4x + 4
= (x - 2)2
c) x2 + 2x + 1 - y2
= (x + 1)2 - y2
= (x + 1 - y)(x + 1 + y)
d) x2 - 4x
= x(x - 4)
e) x2 +10x + 25
= (x + 5)2
g) x2 - 2xy + y2 - 9
= (x - y)2 - 32
= (x - y - 3)(x - y + 3)
h) 2x2 - 2
= 2(x2 - 1)
= 2(x - 1)(x + 1)
i) 5x2 - 5xy + 9x - 9y
= 5x(x - y) + 9(x- y)
= (5x + 9)(x - y)
k) y2 - 4y + 4 - x2
= (y - 2)2 - x2
= (y - 2 - x)(y - 2 + x)
l) x2 - 16
= x2 - 42
= (x - 4)(x + 4)
m) 3x2 - 3xy + 2x -2y
= 3x(x - y) +2(x-y)
= (3x + 2)(x - y)
o) 3x4 - 6x3 + 3x2
= 3x4 - 3x3 - 3x3 + 3x2
= 3x3(x - 1) - 3x2(x - 1)
= (3x3 - 3x2)(x - 1)
= 3x2(x - 1)(x - 1)
= 3x2.(x - 1)2
T
14 tháng 1
\(|x^2+1|-(x^2-4x+4)=3x\\\Rightarrow x^2+1-x^2+4x-4=3x(\text{vì }x^2 + 1 > 0 \forall x )\\\Leftrightarrow 4x-3=3x\\\Leftrightarrow4x-3x=3\\\Leftrightarrow x=3\)
Vậy nghiệm của phương trình là \(x=3\).
NV
Nguyễn Việt Lâm
Giáo viên
14 tháng 1
Do \(x^2+1>0;\forall x\Rightarrow\left|x^2+1\right|=x^2+1\)
Phương trình trở thành:
\(x^2+1-\left(x^2-4x+4\right)=3x\)
\(\Leftrightarrow4x-3=3x\)
\(\Leftrightarrow x=3\)
NH
1
14 tháng 1 2017
Từ \(x^2-2xy+2y^2-2x+6y+5=0\)
\(\Rightarrow\left(x^2-2xy-2x+y^2+2y+1\right)+\left(y^2+4y+4\right)=0\)
\(\Rightarrow\left(x-y-1\right)^2+\left(y+2\right)^2=0\)
\(\Rightarrow\left\{\begin{matrix}\left(x-y-1\right)^2=0\\\left(y+2\right)^2=0\end{matrix}\right.\)\(\Rightarrow\left\{\begin{matrix}x=-1\\y=-2\end{matrix}\right.\)
Thay vào P ta có: \(P=\frac{3x^2y-1}{4xy}=\frac{3\cdot\left(-1\right)^2\cdot\left(-2\right)-1}{4\cdot\left(-1\right)\cdot\left(-2\right)}=-\frac{7}{8}\)
chờ 4 năm nữa em trả lời cho nha?
khó vãi ms nghĩ đc thế này ko biết đúng ko
\(\Leftrightarrow\left|y^2+\left(-2x-2\right)y+x^2-3x-1\right|+4=\left|x^2+3x+2\right|+2x\)\(\Rightarrow\left|y^2+\left(-2x-2\right)y+x^2-3x-1\right|-\left|x^2-3x+2\right|-2x+4=0\)