(√2x-y)^2
Tính
a)(2x^2+y).(2x^2-y)-4x^2+y^2
b)(2x^2+y)^2-(2x^2-y^2)
c)(2x+1)(2x-1)-4x^2
d)(2x^3y+y)^2-(y-2x^3y)^2
a. \(\left(2x^2+y\right)\left(2x^2-y\right)-4x^2+y^2=\left(2x^2\right)^2-y^2-4x^2+y^2\)
\(=4x^4-4x^2\)
b. \(\left(2x^2+y\right)^2-\left(2x^2-y^2\right)=4x^4+4x^2y+y^2-2x^2+y^2\)
\(=4x^4+4x^2y-2x^2+2y^2\)
c. \(\left(2x+1\right)\left(2x-1\right)-4x^2=\left(2x\right)^2-1^2-4x^2=4x^2-1-4x^2=-1\)
d. \(\left(2x^{3y}+y\right)^2-\left(y-2x^{3y}\right)^2\)
\(=\left(2x^{3y}+y+y-2x^{3y}\right)\left(2x^{3y}+y-y+2x^{3y}\right)\)
\(=2y.2.2x^{3y}=4y.2x^{3y}\)
Tính
a)(2x+1).(2x-1)-4x^2
b)(2x^2+y).(2x^2-y)-4x^2+y^2
c)(2x^2+y)^2-(2x^2-y)^2
d)(2x^3y+y)^2_(y-2x^3y)^2
a/ \(\left(2x+1\right)\left(2x-1\right)-4x^2=\left(2x\right)^2-1^2-4x^2\)
\(=4x^2-1-4x^2\)
b/ \(\left(2x^2+y\right)\left(2x^2-y\right)-4x^2+y^2\)
\(=\left(2x^2\right)^2-y^2-4x^2+y^2=4x^4-y^2-4x^2+y^2=4x^4-4x^2\)
c/ \(\left(2x^2+y\right)^2-\left(2x^2-y\right)^2\)
\(=\left(2x^2+y+2x^2-y\right)\left(2x^2+y-2x^2+y\right)\)
\(=4x^2\cdot2y=8x^2y\)
d/ \(\left(2x^3y+y\right)^2-\left(y-2x^3y\right)^2=\left(2x^3y+y\right)^2-\left(2x^3y-y\right)^2\)
\(=\left(2x^3y+y+2x^3y-y\right)\left(2x^3y+y-2x^3y+y\right)\)
\(=4x^3y\cdot2y=8x^3y^2\)
tính
a)(2x+1).(2x-1)-4x^2
b)(2x^2+y)(2x^2-y)-4x^2+y^2
c)(2x^2+y)^2-(2x^2-Y)^2
2/3x^2(2x^2-y/3)-2x^2(2x^2-1)+(2x^2-y/3)(1-y/3)(2x^2-1)
CM tổng sau :
\(\frac{2x+y}{2x^2-xy}+\frac{8y}{y^2-4x^2}+\frac{2x-y}{2x^2+xy}=\frac{2.\left(2x-y\right)}{x.\left(2x+y\right)}.\)
*Cộng các phân thức sau: a) x^2/x+1 + 2x/x^2-1 + 1/1+x+1 b) 2x+y/2x^2-y + 8y/y^2-4x^2+2x-y/2x^2+xy c) 1/x-y +3xy/y^3-x^3 + x-y/x^2+xy+y^2
a, \(\frac{x^2}{x+1}+\frac{2x}{x^2-1}+\frac{1}{x+1}+1\)
\(=\frac{x^2\left(x-1\right)}{\left(x+1\right)\left(x-1\right)}-\frac{2x}{\left(x-1\right)\left(x+1\right)}+\frac{x-1}{\left(x+1\right)\left(x-1\right)}+\frac{\left(x+1\right)\left(x-1\right)}{\left(x+1\right)\left(x-1\right)}\)
\(=\frac{x^3-x^2-2x+x-1-x^2-1}{\left(x-1\right)\left(x+1\right)}\)
\(=\frac{x^3-2x^2-x-2}{\left(x-1\right)\left(x+1\right)}\)
*Cộng các phân thức sau:a) x^2/x+1 + 2x/x^2-1 + 1/1+x+1 b) 2x+y/2x^2-y + 8y/y^2-4x^2+2x-y/2x^2+xy
a) \(\dfrac{x^2}{x+1}+\dfrac{2x}{x^2-1}+\dfrac{1}{1+x+1}\) \(=\dfrac{x^2.\left(x-1\right)\left(x+2\right)}{\left(x+1\right).\left(x-1\right)\left(x+2\right)}+\dfrac{2x.\left(x+2\right)}{\left(x-1\right).\left(x+1\right).\left(x+2\right)}+\dfrac{\left(x-1\right).\left(x+1\right)}{\left(x-1\right)\left(x+1\right).\left(x+2\right)}\)
\(=\dfrac{x^2.\left(x-1\right).\left(x+2\right)+2x.\left(x+2\right)+\left(x-1\right)\left(x+1\right)}{\left(x+1\right).\left(x-1\right).\left(x+2\right)}\)
\(=\dfrac{x^4+x^3-2x^2+2x^2+4x+x^2-1}{\left(x-1\right)\left(x+1\right).\left(x+2\right)}\)
\(=\dfrac{x^4+x^3+x^2+4x-1}{\left(x^2-1\right).\left(x+2\right)}\)
\(=\dfrac{x^4+x^3+x^2+4x-1}{x^3+2x^2-x-2}\)
phân tích đa thức thành nhân tửa) B=5x(x-4y)-4y(y-5x)
b)M=(2x+y)^2-(2x+y)(2x-y)=y(x-y)
c)N=(a-3b)^2-(a+3b)^2-(a-1)(b-2)
d)P=(2x-5)(2x+5)-(2x+1)^2
e)Q=(y-3)(y+3)(y^2+9)-(y^2+2)(y^2-2)
Giải hệ phương trình :
8(2x+y)^2 - 10 (4x^2 - y^2) - 3 (2x-y)^2 = 0
2x+y - 2/(2x-y) = 2
\(\hept{\begin{cases}8\left(2x+y\right)^2-10\left(2x+y\right)\left(2x-y\right)-3\left(2x-y\right)^2=0\\2x+y-\frac{2}{2x-y}=2\end{cases}}\)
\(\hept{\begin{cases}8\left(2x+y\right)^2-10\left(2x+y\right)\left(2x-y\right)-3\left(2x-y\right)^2=0\\\left(2x+y\right)\left(2x-y\right)-2=2\left(2x-y\right)\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}8\left(2x+y\right)^2-10\left(2x+y\right)\left(2x-y\right)-3\left(2x-y\right)^2=0\\\left(2x+y\right)\left(2x-y\right)=2\left(2x-y\right)+2\end{cases}}\)
\(\Rightarrow8\left(2+\frac{2}{2x-y}\right)^2-20\left(2x-y\right)-20-3\left(2x-y\right)^2=0\)
Giải pt này vs ẩn là (2x-y) được nghiệm là 2
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