mn giai giup em voi
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a: AK<AQ
=>K nằm giữa A và Q
=>AK+KQ=AQ
=>KQ=1cm
b: AK và AC là hai tia đối nhau
=>A nằm giữa K và C
mà AK=AC
nen A là trung điểm của KC
c: BK=1,5+3=4,5cm>AQ
1 plays
2 are reading
3 sing
4 do - do, help
5 is teaching
7 visited
8 doesn't like
9 watch
10 gets - has - brushes - goes - has
11 played - was
12 met
13 are going to have
14 did - do , planted
15 didn't come
16 paint
17 taught
18 have never been
19 takes
20 have - had
21 received
22 is going to invite
23 is waiting
24 talked
25 is going to travel
26 went - didn't buy
27 doesn't learn - will fail
28 washes
29 will be - watches
30 will phone
2 are reading
3 sings
4 do - do - help
5 is teaching
7 visited
8 doesn't like
9 watch
10 gets - has
6. 10 brushes - goes
6. 30 has
11 played - was
12 met
13 will have
14 did - do - planted
15 didn't come
16 paint
17 taught
\(\left(3-x\right)\left(x+7\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}3-x=0\\x+7=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=3\\x=-7\end{cases}}}\)
Vậy x=3; x=-7
1.frightened
2.frightening
3.depressing
4.depressed
5.excited
6.interesting
7.thrilling
8.embarrassed
9.exhausted
10.boring
frightened
frightening
depressing
depressed
excited
interesting
thrilling
embarrassed
exhausted
boring
Bài 4 :
a, \(\sqrt{x}-1=3\Leftrightarrow\sqrt{x}=4\Leftrightarrow x=16\)ĐK : x >= 0
b, \(\sqrt{x^2-10x+25}=7-2x\Leftrightarrow\sqrt{\left(x-5\right)^2}=7-2x\Leftrightarrow\left|x-5\right|=7-2x\)
ĐK : \(7-2x\ge0\Leftrightarrow-2x\ge-7\Leftrightarrow x\le\frac{7}{2}\)
TH1 : \(x-5=7-2x\Leftrightarrow3x=12\Leftrightarrow x=4\)( ktm )
TH2 : \(x-5=2x-7\Leftrightarrow x=2\)( tm )
c, \(\sqrt{9-12x+4x^2}=4\Leftrightarrow\sqrt{\left(3-2x\right)^2}=4\Leftrightarrow\left|3-2x\right|=4\)
TH1 : \(3-2x=4\Leftrightarrow x=-\frac{1}{2}\)
TH2 : \(3-2x=-4\Leftrightarrow-2x=-7\Leftrightarrow x=\frac{7}{2}\)
Bài 2 :
a, Để A có nghĩa khi \(3x+9\ge0\Leftrightarrow x+3\ge0\Leftrightarrow x\ge-3\)
b, Để B có nghĩa khi \(\frac{-5}{-x-7}\ge0\Rightarrow-x-7\le0\Leftrightarrow x+7\ge0\Leftrightarrow x\ge-7\)và \(x\ne-7\)
\(\Rightarrow x>-7\)