Bài 1 :

\(a,6^3.6^7.6^5=6^{3+7+5}=6^{15}\)

\(b,17^9:17^5:17^2=17^{9-5-2}=17^2\)

\(c,=\left(3^3\right)^3.3^3=3^9.3^3=3^{9+3}=3^{12}\)

\(d,=\left(2^4\right)^3.\left(2^6\right)^5=2^{12}.2^{30}=2^{12+30}=2^{42}\)

Bài 2 :

\(a,11^{60}:11^{58}=11^{60-58}=11^2=121\)

\(b,8^{10}:8^5:8^4=8^{10-5-4}=8^1=8\)

\(c,=\left(5^2\right)^9:\left(5^3\right)^5=5^{18}:5^{15}=5^{18-15}=5^3=125\)

\(d,=\left(2^4\right)^5:\left(2^2\right)^6:\left(2^3\right)^2=2^{20}:2^{12}:2^6=2^{20-12-6}=2^2=4\)

\(e,=10^5.\left(10^2\right)^5.\left(10^3\right)^2=10^5.10^{10}.10^6=10^{5+10+6}=10^{21}\)

Bài 3:

a)\(58.75+58.50-58.25\)

=\(58.\left(75+50-25\right)\)

=\(58.100\)

=\(5800\)

b)\(27.39+27.63-2.27\)

=\(27.\left(39+63-2\right)\)

=\(27.100\)

=\(2700\)

c)\(156.25+5.156+156.14+36.156\)

=\(156.\left(25+5+14+36\right)\)

=\(156.80\)
=\(12480\)

d)\(12.35+35.182-35.94\)

=\(35.\left(12+182-94\right)\)

=\(35.100\)

=\(3500\)

e)\(48.19+48.115+67.104\)

=\(48.\left(19+115\right)+67.104\)

=\(48.134+67.104\)

=\(48.67+48.67+67.104\)

=\(67.\left(48+48+104\right)\)

=\(67.200\)

=\(13400\)

f)\(128.72+128.67+128.72+11.72\)

=\(128.\left(72+67\right)+72.\left(128+11\right)\)

=\(128.139+72.139\)

=\(139.\left(72+128\right)\)

=\(139.200\)

=\(27800\)

1 C => hers

2 B => will use

3 D => their

4 A => will be pedaling

5 A => travel

6 C => less

7 D => have they

8 D => than

9 A => worked

10 B => fewer

Ex1 ko có verb à

Ex2

1 like

2 listen

3 wears

4 teaches

5 do

6 goes

7 comes

8 goes

9 watch

10 walks

11 is

12 washes

13 studies

14 wants

15 plays

16 buys

17 studies

18 tries

19 washes

20 cries

21 says

22 flies

23 don't have

verb là tobe ạ

Bài 3:

1, Áp dụng t/c dtsbn:

\(\dfrac{x}{6}=\dfrac{y}{4}=\dfrac{z}{3}=\dfrac{z-x}{3-6}=\dfrac{-21}{-3}=7\\ \Rightarrow\left\{{}\begin{matrix}x=42\\y=28\\z=21\end{matrix}\right.\)

2, Áp dụng t/c dtsbn:

\(\dfrac{x}{3}=\dfrac{y}{5}=\dfrac{z}{7}=\dfrac{2x+3y-z}{6+15-7}=\dfrac{-14}{14}=-1\\ \Rightarrow\left\{{}\begin{matrix}x=-3\\y=-5\\z=-7\end{matrix}\right.\)

Bài 4: 

Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:

\(\dfrac{x}{\dfrac{1}{2}}=\dfrac{y}{\dfrac{1}{3}}=\dfrac{z}{\dfrac{1}{4}}=\dfrac{x+y+z}{\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}}=\dfrac{130}{\dfrac{13}{12}}=120\)

Do đó: x=60; y=40; z=30

mở bài là giới thiệu về cụ nha mn em viết lộn ạ 

thân bài là đóng góp ạ 

Câu 6:

a: =12x^2+4x-3x-1-5x^2+15x-x^2+7x-12

=6x^2+23x-13

b: =5x^2+5x-2x-2-3x^3+3x^2+9x-2x(x^2-9x+20)

=-3x^3+8x^2+14x-2-2x^3+18x^2-40x

=-5x^3+26x^2-26x-2

bằng -49/10 nha bạn!

b=5/46