giúp gấp từ phần b-phần g, thanks nhiều ạ <3
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20 tháng 12 2023
e: \(\left(-4156+2021\right)-\left(119+2021-4156\right)\)
\(=-4156+2021-119-2021+4156\)
\(=\left(-4156+4156\right)+\left(2021-2021\right)-119\)
=0+0-119
=-119
g: \(315\cdot75-\left(15\cdot100-315\cdot25\right)\)
\(=315\cdot75-15\cdot100+315\cdot25\)
\(=315\left(75+25\right)-15\cdot100\)
\(=315\cdot100-15\cdot100=300\cdot100=30000\)
h: \(\left(-489\right)\cdot125-\left(125\cdot11-500\cdot25\right)\)
\(=-489\cdot125-125\cdot11+500\cdot25\)
\(=125\left(-489-11\right)+500\cdot25\)
\(=125\cdot\left(-500\right)+500\cdot25\)
\(=500\left(-125+25\right)\)
\(=500\cdot\left(-100\right)=-50000\)
Bài 2:
a: \(-415-3\left(2x-1\right)^2=-490\)
=>\(3\left(2x-1\right)^2+415=490\)
=>\(3\left(2x-1\right)^2=75\)
=>\(\left(2x-1\right)^2=25\)
=>\(\left[{}\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=6\\2x=-4\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
N
2
11 tháng 7 2021
21. massive
22. openness
23. operation
24. punctuality
25. simplicity
26. inhabitable
NT
1
15 tháng 1 2024
z4:
\(\dfrac{24}{148}=\dfrac{6}{37}=\dfrac{108}{37\cdot18}\)
\(\dfrac{-14}{-36}=\dfrac{7}{18}=\dfrac{7\cdot37}{18\cdot37}=\dfrac{259}{37\cdot18}\)
mà 108<259
nên \(\dfrac{24}{148}< \dfrac{-14}{-36}\)
z5: \(\dfrac{-26}{-72}=\dfrac{26}{72}< 1\)
\(1< \dfrac{45}{20}=\dfrac{-45}{-20}\)
Do đó: \(\dfrac{-26}{-72}< \dfrac{-45}{-20}\)
z6: \(\dfrac{14}{42}=\dfrac{1}{3}=\dfrac{1\cdot4}{3\cdot4}=\dfrac{4}{12}\)
\(\dfrac{21}{28}=\dfrac{3}{4}=\dfrac{3\cdot3}{4\cdot3}=\dfrac{9}{12}\)
mà 4<9
nên \(\dfrac{14}{42}< \dfrac{21}{28}\)
z7: \(\dfrac{-14}{-56}=\dfrac{1}{4}=\dfrac{5}{20}\)
\(\dfrac{21}{35}=\dfrac{3}{5}=\dfrac{3\cdot4}{5\cdot4}=\dfrac{12}{20}\)
mà 5<12
nên \(\dfrac{-14}{-56}< \dfrac{21}{35}\)
z8: \(10A=\dfrac{10^{201}+10}{10^{201}+1}=1+\dfrac{9}{10^{201}+1}\)
\(10B=\dfrac{10^{202}+10}{10^{202}+1}=1+\dfrac{9}{10^{202}+1}\)
\(10^{201}+1< 10^{202}+1\)
=>\(\dfrac{9}{10^{201}+1}>\dfrac{9}{10^{202}+1}\)
=>\(\dfrac{9}{10^{201}+1}+1>\dfrac{9}{10^{202}+1}+1\)
=>10A>10B
=>A>B
NT
1
7 tháng 1 2024
a: \(248\left(13-197\right)+197\left(248-13\right)\)
\(=248\cdot13-248\cdot197+197\cdot248-197\cdot13\)
\(=248\cdot13-197\cdot13\)
\(=51\cdot13=663\)
b: \(146\left(295-39\right)-295\left(146-39\right)\)
\(=146\cdot295-146\cdot39-295\cdot146+295\cdot39\)
\(=295\cdot39-146\cdot39\)
\(=39\cdot149=5811\)
c: \(\left(-245\right)\left(45-948\right)-45\left(948-245\right)\)
\(=-245\cdot45+245\cdot948-45\cdot948+45\cdot245\)
\(=245\cdot948-45\cdot948\)
\(=200\cdot948=189600\)
d: \(\left(-3\right)^4-7\cdot\left(-2\right)\cdot\left(-3\right)^3+4^3-\left(-2024\right)^0\)
\(=81+14\cdot\left(-27\right)+64-1\)
\(=144-378=-234\)
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
11 tháng 2 2023
\(\dfrac{20\times30}{3\times6\times25}\) = \(\dfrac{4\times5\times6\times5}{3\times6\times5\times5}\) = \(\dfrac{5\times6\times5\times4}{5\times6\times5\times3}\) =\(\dfrac{4}{3}\)
\(\dfrac{15\times28}{35\times20}\) = \(\dfrac{5\times3\times7\times4}{5\times7\times4\times5}\) = \(\dfrac{5\times7\times4\times3}{5\times7\times4\times5}\) = \(\dfrac{3}{5}\)
LH
1
2 tháng 3
B. WRITING
I. Circle the letter A, B, C or D under the word/ phrase that needs correcting.
B (if to tell → whether to tell)
C (didn’t have → wouldn’t have)
B (suggest → suggests)
II. Rewrite these sentences begin with the words given.
She asked me how to deal with school pressure.
He advised me to call the helpline because they could give me good advice.
III. Write an email (100 - 120 words) to a friend of yours telling him/her about one city that you would like to visit the most.
Dear [Friend's Name],
I hope you're doing well! I wanted to share with you about a city I’m really excited to visit – Paris, France. I’ve always dreamed of exploring its rich culture, stunning architecture, and delicious cuisine. The Eiffel Tower, Louvre Museum, and Notre-Dame Cathedral are some of the iconic landmarks I can’t wait to see.
What attracts me most is the city’s artistic vibe and romantic atmosphere. I plan to visit during the spring, around April, when the weather is pleasant, and the flowers are in full bloom. I’d love to stroll along the Seine River and enjoy a coffee at a charming café.
I hope to make this trip next year. Let me know if you have any tips or recommendations!
Best,
[Your Name]
=)))
Lời giải:
b. $-138-3(2x^2-1)=-169$
$3(2x^2-1)=-148-(-169)=21$
$2x^2-1=21:3=7$
$2x^2=7+1=8$
$x^2=4=2^2=(-2)^2\Rightarrow x=\pm 2$
c.
$4(-x+5)^2-15=21$
$4(-x+5)^2=21+15=36$
$(-x+5)^2=36:4=9=3^2=(-3)^2$
$\Rightarrow -x+5=3$ hoặc $-x+5=-3$
$\Rightarrow x=2$ hoặc $x=8$
d.
$4(-3x^2-145)=-628$
$-3x^2-145=-628:4=-157$
$3x^2+145=157$
$3x^2=157-145=12$
$x^2=12:3=4=2^2=(-2)^2$
$\Rightarrow x=\pm 2$
e.
$252-3(-x-5)^2=225$
$3(-x-5)^2=252-225=27$
$(-x-5)^2=27:3=9$
$(x+5)^2=3^2=(-3)^2$
$\Rightarrow x+5=3$ hoặc $x+5=-3$
$\Rightarrow x=-2$ hoặc $x=-8$