giúp mk vs ạ mai mk hc rồi
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NT
1
28 tháng 10 2021
\(\Leftrightarrow\sqrt{x+4}\left(\sqrt{x-4}-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+4=0\\x-4=4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-4\\x=8\end{matrix}\right.\)
31 tháng 10 2021
a, ĐKXĐ: \(x\le2\)
\(\sqrt{4-2x}=5\\ \Leftrightarrow4-2x=25\\ \Leftrightarrow2x=-21\\ \Leftrightarrow x=-10,5\left(tm\right)\)
b, ĐKXĐ: \(x\ge-1\)
\(\sqrt{25\left(x+1\right)}+\sqrt{9x+9}=16\\ \Leftrightarrow5\sqrt{x+1}+\sqrt{9\left(x+1\right)}=16\\ \Leftrightarrow5\sqrt{x+1}+3\sqrt{x+1}=16\\ \Leftrightarrow8\sqrt{x+1}=16\\ \Leftrightarrow\sqrt{x+1}=2\\ \Leftrightarrow x+1=4\\ \Leftrightarrow x=3\)
c, \(\sqrt{4x^2+12x+9}=4\Leftrightarrow4x^2+12x+9=16\\ \Leftrightarrow4x^2+12x-7=0\\ \Leftrightarrow\left(4x^2-2x\right)+\left(14x-7\right)=0\\ \Leftrightarrow2x\left(2x-1\right)+7\left(2x-1\right)=0\\ \Leftrightarrow\left(2x-1\right)\left(2x+7\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-\dfrac{7}{2}\end{matrix}\right.\)
31 tháng 10 2021
a: \(\Leftrightarrow4-2x=25\)
hay \(x=-\dfrac{21}{2}\)
c: \(\Leftrightarrow\left|2x+3\right|=4\)
\(\Leftrightarrow\left[{}\begin{matrix}2x+3=4\\2x+3=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-\dfrac{7}{2}\end{matrix}\right.\)
20 tháng 5 2021
part 1
1 where
2 which
3 important
4 traditional
5 of
6 even though
part 2
1G 2A 3F 4D 5C 6B
part 3
1 not watching
2 would arrive
3 would pay
4 playing
5 has worked
6 harmed
7 unsuccessful
8 richly
part 4
1 internation -> international
2 write -> be written
part 5
1 have to be taken
2 spends 2 hours doing
3 unless someone puts
4 which I visited
part 6
1 natural
2 economically
3 resources
4 before
part 7
1T 2T 3F 4T
DT
Đỗ Thanh Hải
CTVVIP
20 tháng 5 2021
Part 1
1 friendliness
2 were
3 after
4 written
5 correspond
6 which
Part2
1 - D
2 - C
3 - A
4 - G
5 - E
6 - F
Part 3
1 should do
2 visiting
3 cut
4 made
5 has learnt
6 modernize
7commercial
8 untreated
Part 4
1 will => would
2 carefully => careful
Part 5
1 I would pay a visit to
2 planted trees along the
3 going to be sent
4 which I borrowed from
Part 6
1 subtances
2 Industrial
3 frequently
4 that
20 tháng 5 2021
Part 1
1 friendliness
2 were
3 after
4 written
5 correspond
6 which
Part 2
1D 2C 3A 4G 5E 6F
Part3
1 have to do
2 visiting
3 cut
4 was making
5 has learnt
6 modernize
7 commercially
8 mistreated
Part 4
1 will -> would
2 carefully -> careful
Part 5
1 to pay a visit
2 planted trees along the
3 going to be sent
4 that I borrowed from
Part 6
1 substances
2 industrial
3 naturally
4 that
Part 7
1F 2F 3T 4T
2 tháng 1 2022
1, C=> visited
2, B=> the last bus
3, D=> between
4, B=> such
5, C=>to see
6, C=>widely
7, D=>in Friday afternoon
8, B=>information
13 tháng 10 2021
2: Xét ΔABC vuông tại A có
\(BC^2=AB^2+AC^2\)
hay \(AC=\dfrac{14\sqrt{2}}{5}\left(cm\right)\)
Xét ΔABC vuông tại A có
\(\sin\widehat{C}=\dfrac{41}{57}\)
\(\Leftrightarrow\widehat{C}\simeq46^0\)
hay \(\widehat{B}=44^0\)