( x^2 +x ^3 -xy^2 +3 ) + ( x^3 +xy ^2 - xy -6)
Tìm đa thức b biết
B-(3\(x^6\)-4\(xy^5\)+\(\dfrac{1}{3}\)\(xy^2\)-\(\dfrac{3}{2}\))=(7\(x^6\)-\(\dfrac{1}{2}xy^5-xy^2-\dfrac{1}{3}\))
B-(\(3x^6-4xy^5+\dfrac{1}{3}xy^2\))=
B= \(\left(7x^6-\dfrac{1}{2}xy^5-xy^2-\dfrac{1}{3}\right)+\left(3x^6-4xy^5+\dfrac{1}{3}xy^2-\dfrac{3}{2}\right)\)
B= \(7x^6-\dfrac{1}{2}xy^5-xy^2-\dfrac{1}{3}+3x^6-4xy^5+\dfrac{1}{3}xy^2-\dfrac{3}{2}\)
B= \(7x^6+3x^6-\dfrac{1}{2}xy^5-4xy^5-xy^2+\dfrac{1}{3}xy^2-\dfrac{1}{3}+\dfrac{2}{3}\)
B= \(10x^6-\dfrac{9}{2}xy^5-\dfrac{2}{3}xy^2+\dfrac{1}{3}\)
Rút gọn biểu thức.
a)A=(x+2)3+(x-2)3-2x(x2+12)
b)B=(xy+2)3-6(xy+2)2+12(xy+2)-8
a) A = (x + 2)³ + (x - 2)³ - 2x(x² + 12)
= x³ + 6x² + 12x + 8 + x³ - 6x² + 12x - 8 - 2x² - 24x
= (x³ + x³) + (6x² - 6x² - 2x²) + (12x + 12x - 24x) + (8 - 8)
= 2x³ -2x²
b) B = (xy + 2)³ - 6(xy + 2)² + 12(xy + 2) - 8
= (xy + 2 - 2)³
= (xy)³
= x³y³
Tìm x ,y là số tự nhiên ,biết
1) xy=2. 2) xy=5. 3)xy =6. 4)xy=8. 5)xy=12
6) xy=42 (x<y)
a, x=1; y=2 => 12
x=2; y=1 => 21
b, x=1; y=5 => 15
x=5; y=1 => 51
c, x=1; y=6 => 16
x=6;y=1 => 61
x=2; y=3=> 23
x=3; y=2 => 32
d, x=1; y=8 => 18
x=2; y=4 => 24
x=4; y=2 => 42
x=8; y=1 => 81
5,
x=3; y=4 => 34
x=4; y=3 => 43
x=2; y=6 => 26
x=6; y=2 => 62
Giải hệ pt
1/\(\left\{{}\begin{matrix}4x\sqrt{y+1}+8x=\left(4x^2-4x-3\right)\sqrt{x+1}\\\dfrac{x}{x+1}+x^2=\left(y+2\right)\sqrt{\left(x+1\right)\left(y+1\right)}\end{matrix}\right.\)
2/\(\left\{{}\begin{matrix}x\sqrt{y^2+6}+y\sqrt{x^2+3}=7xy\\x\sqrt{x^2+3}+y\sqrt{y^2+6}=x^2+y^2+2\end{matrix}\right.\)\(\left\{{}\begin{matrix}x\sqrt{y^2+6}+y\sqrt{x^2+3}=7xy\\x\sqrt{x^2+3}+y\sqrt{y^2+6}=x^2+y^2+2\end{matrix}\right.\)
3/\(\left\{{}\begin{matrix}\left(2x+y-1\right)\left(\sqrt{x+3}+\sqrt{xy}+\sqrt{x}\right)=8\sqrt{x}\\\left(\sqrt{x+3}+\sqrt{xy}\right)^2+xy=2x\left(6-x\right)\end{matrix}\right.\)\(\left\{{}\begin{matrix}\left(2x+y-1\right)\left(\sqrt{x+3}+\sqrt{xy}+\sqrt{x}\right)=8\sqrt{x}\\\left(\sqrt{x+3}+\sqrt{xy}\right)^2+xy=2x\left(6-x\right)\end{matrix}\right.\)
4/\(\left\{{}\begin{matrix}\sqrt{xy+x+2}+\sqrt{x^2+x}-4\sqrt{x}=0\\xy+x^2+2=x\left(\sqrt{xy+2}+3\right)\end{matrix}\right.\)\(\left\{{}\begin{matrix}\sqrt{xy+x+2}+\sqrt{x^2+x}-4\sqrt{x}=0\\xy+x^2+2=x\left(\sqrt{xy+2}+3\right)\end{matrix}\right.\)
m.n giúp e mấy bài này vs ạ!!
Rút gọn P=x2y+x3-xy2+3+x3+xy2-xy-6
Câu 2: (1,5 điểm) Hãy thu gọn các đơn thức,đa thức sau:
a) A = - ( 6 . 8 x x 7 6 3 y y ) ( 3 )
b) B xy xy xy xy = - - + + + 7 2 8 5 6
xy - x + y = -3 x^2 + y^2 - x + y + xy = 6
\(\Leftrightarrow\left\{{}\begin{matrix}3xy-3\left(x-y\right)=-9\\x^2+y^2+xy-\left(x-y\right)=6\end{matrix}\right.\)
Trừ vế cho vế:
\(x^2+y^2-2xy+2\left(x-y\right)=15\)
\(\Leftrightarrow\left(x-y\right)^2+2\left(x-y\right)-15=0\Rightarrow\left[{}\begin{matrix}x-y=3\\x-y=-5\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}y=x-3\\y=x+5\end{matrix}\right.\)
Thế vào pt đầu:
\(\Rightarrow\left[{}\begin{matrix}x\left(x-3\right)-x+x-3=-3\\x\left(x+5\right)-x+x+5=-3\end{matrix}\right.\)
\(\Leftrightarrow...\)
Phân tích đa thức 3\(x^2\)y + 6\(xy^2\) – 9xy thành nhân tử. Kết quả là:
A. 3(\(x^2y\) + 2\(xy^2\) – 3xy - 3). B. 3y(\(x^2\) + 2xy – 3x). C. xy(3x + 6y - 9). D. 3xy(x + 2y – 3).
a) Cho \(x + y = 12\) và \(xy = 35\). Tính \({\left( {x - y} \right)^2}\)
b) Cho \(x - y = 8\) và \(xy = 20\). Tính \({\left( {x + y} \right)^2}\)
c) Cho \(x + y = 5\) và \(xy = 6\). Tính \({x^3} + {y^3}\)
d) Cho \(x - y = 3\) và \(xy = 40\). Tính \({x^3} - {y^3}\)
`a, (x-y)^2 = (x+y)^2 - 4xy = 12^2 - 35 . 4 = 144 - 140 = 4`.
`b, (x+y)^2 = (x-y)^2 + 4xy = 8^2 + 20.4 = 64 + 80 = 144`
`c, x^3 + y^3 = (x+y)^3 - 3xy(x+y) = 5^3 - 3 . 6 . 5 = 125 - 90 = 35`
`d, x^3 - y^3 = (x-y)^3 - 3xy(x-y) = 3^3 - 3 .40 . 3 = 27 - 360 = -333`.