mọi người giúp e bài 2 vói bài 3 với
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2.a) = x^12 : x^6 = x^6
b) = (-x)^2=x^2
c) = 1/2.xy^3
d) -3/2.x^2.y
e) = (-xy)^7
f) = -4x^2 + 4xy - 6y^2
g) = xy - 2x + 4y
Bài 1:
a: A chia hết cho B
b: A chia hết cho B
c: A không chia hết cho B
d: A không chia hết cho B
1:
1: Khi x=36 thì \(A=\dfrac{36-4}{3+3}=\dfrac{32}{6}=\dfrac{16}{3}\)
2: \(B=\dfrac{2x+6\sqrt{x}-x-9\sqrt{x}}{x-9}=\dfrac{x-3\sqrt{x}}{x-9}=\dfrac{\sqrt{x}}{\sqrt{x}+3}\)
3: \(P=A:B=\dfrac{\sqrt{x}}{\sqrt{x}+3}:\dfrac{x-4}{\sqrt{x}+3}=\dfrac{\sqrt{x}}{x-4}\)
P<0
=>x-4<0
=>0<=x<4
=>\(x\in\left\{0;1;2;3\right\}\)
Gọi O là giao điểm của AC, BD.
Gọi G là giao điểm SO và AM.
Qua G vẽ PQ // BD (P thuộc SB, Q thuộc SD), (APMQ) là mp(P) cần tìm.
G là trọng tâm tam giác SBD →\(\frac{SG}{SO}=\frac{2}{3}\)
PQ // BD → \(\frac{SP}{SB}=\frac{SQ}{SD}=\frac{SG}{SO}=\frac{2}{3}\)
\(V_{S.APMQ}=V_{S.APM}+V_{S.AQM}\)
\(=\frac{SP}{SB}\cdot\frac{SM}{SC}\cdot V_{S.ABC}+\frac{SQ}{SD}\cdot\frac{SM}{SC}\cdot V_{S.ACD}\)
\(=\frac{1}{3}V_{S.ABC}+\frac{1}{3}V_{S.ACD}=\frac{2}{3}V_{S.ABC}=\frac{2}{3}\cdot\frac{1}{2}\cdot V_{S.ABCD}=\frac{1}{3}V_{S.ABCD}\)
a: =>x-4=0 hoặc x+5=0
=>x=4 hoặc x=-5
b: =>39/7:x=13
hay x=3/7
c: \(\Leftrightarrow\left(4.5-2x\right)=\dfrac{11}{4}:\dfrac{4}{9}=\dfrac{99}{16}\)
\(\Leftrightarrow2x=-\dfrac{27}{16}\)
hay x=-27/32
d: \(\Leftrightarrow x\cdot\dfrac{19}{15}=684\)
hay x=540
a. \(\left[{}\begin{matrix}x-4=0\\x+5=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-5\end{matrix}\right.\)
b.\(\Leftrightarrow\dfrac{39}{7}:x=13\)
\(\Leftrightarrow x=13.\dfrac{39}{7}\)
\(\Leftrightarrow x=\dfrac{507}{7}\)
c.\(\Leftrightarrow4,5-2x=\dfrac{99}{16}\)
\(\Leftrightarrow-2x=\dfrac{27}{16}\)
\(\Leftrightarrow x=-\dfrac{27}{32}\)
1 Where did you go?
2 Who did you go with?
3 How did you get there?
4 What did you do during the day?
5 Did you have a good time?
1. Where did you go?
Where was you going?
2. Who did you go with?
Who was you going with?
3. How did you get there?
How was you getting there?
\(Bài.1:\\ a,3x-9y=3\left(x-3y\right)\\ b,x^2-5x=x\left(x-5\right)\\ c,\left(x-3\right)\left(x-5\right)-\left(2x+1\right)\left(3-x\right)=\left(x-3\right)\left(x-5\right)+\left(x-3\right)\left(2x+1\right)\\ =\left(x-3\right)\left(x-5+2x+1\right)=\left(x-3\right)\left(3x-4\right)\\ d,3x^3+6x^2+3x=3x\left(x^2+2x+1\right)=3x\left(x+1\right)^2\\ e,3\left(x+5\right)-x^2-5x=3\left(x+5\right)-x\left(x+5\right)\\ =\left(x+5\right)\left(3-x\right)\)
\(Bài.2:\\ a,x^3-9x=0\\ \Leftrightarrow x.\left(x^2-9\right)=0\\ \Leftrightarrow x\left(x-3\right)\left(x+3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x+3=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-3\\x=3\end{matrix}\right.\\ b,5x\left(x+2\right)-3\left(x+2\right)=0\\ \Leftrightarrow\left(5x-3\right)\left(x+2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}5x-3=0\\x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{5}\\x=-2\end{matrix}\right.\\ c,x^2-7x=0\\ \Leftrightarrow x\left(x-7\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x-7=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=7\end{matrix}\right.\)
Bài 2 lấy VT nhân phân phối vào rồi rút gọn là đc