giúp em với mn em đg cần gấp
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Lời giải:
Đặt $xy=k$. Ta có:
$x_1y_1=k=x_2y_2$
Thay $x_1=6; x_2=-9\Rightarrow 6y_1=-9y_2$
$\Leftrightarrow y_1=-1,5y_2$
$y_1-y_2=10$
$-1,5y_2-y_2=10$
$-2,5y_2=10$
$y_2=-4$
$y_1=-1,5y_2=-1,5.(-4)=6$
\(11,\\ a,M=\dfrac{1+\sqrt{a}}{\sqrt{a}\left(\sqrt{a}-1\right)}\cdot\dfrac{\left(\sqrt{a}-1\right)^2}{\sqrt{a}+1}=\dfrac{\sqrt{a}-1}{\sqrt{a}}\\ b,M=\dfrac{\sqrt{a}-1}{\sqrt{a}}=1-\dfrac{1}{\sqrt{a}}< 1\left(\dfrac{1}{\sqrt{a}}>0\right)\)
\(9,\\ a,=\left|2-\sqrt{7}\right|=\sqrt{7}-2\\ b,=5\sqrt{3}+4\sqrt{3}-10\sqrt{3}=-\sqrt{3}\\ c,=3-4+2=1\\ d,=6\sqrt{3a}-4\sqrt{3a}=2\sqrt{3a}\\ 10,\)
a, Áp dụng HTL: \(x=\sqrt{9\cdot25}=15\)
b, Áp dụng HTL: \(\left\{{}\begin{matrix}8^2=10x\\y^2=x\left(x+10\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=6,4\\y=\sqrt{6,4\cdot16,4}\approx10,245\end{matrix}\right.\)
1, That
2, This
3, that
4, those
5, these - that
6, these
7, this
8, that
9, that
10, this
11, those
12, this
13, it
14, these
15, them
16, those
my - your
my
I - my
her
Nam and Lan's teacher
is
Her
Those students' school bags
your
He
is - your - She
its
her
His
their
hers
him
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1 friendly
2 creative
3 boring
4 funny
5 sensitive
6 outgoing
7 lazy
8 impatient
9 active
10 quiet
1.Yes, they do
2..Yes, it is
3.People buy fruits and flowers from the market and decorate their house
4.People visit their family and friends