minh ko biet

= 8 /17 *[ 20/15 + 4/15 - 9/15

=8/17 * 1 

8 /17

Tìm x

a) x - 1,27 = 13,5 : 4,5

x - 1,27 = 3

x = 1,27 + 3

x = 4,27

b) 8/3 - x = 2/5

x = 8/3 - 2/5

x = 34/15

Phương pháp giải:

- Đặt tính: Viết phép tính sao cho các chữ số cùng hàng thẳng cột với nhau.

- Tính: Trừ các số rồi điền kết quả vào chỗ trống.

Lời giải chi tiết:

a)

b)

c)

`@` `\text {Ans}`

`\downarrow`

`x^3 = 125`

`=> x^3 = 5^3`

`=> x = 5`

Vậy, `x = 5`

_____

`4^5 \div 4^3`

`=`\(4^{5-3}\)

`= 4^2`

______

\(8^{12}\cdot8^3\div8^{15}\)

`=`\(8^{12+3-15}\)

`=`\(8^0=1\)

______

\(7^{15}\div7^{13}\)

`=`\(7^{15-13}\)

`=`\(7^2\)

_______

\(17^{15}\cdot17^{10}\div17^{22}\)

`=`\(17^{15+10-22}\)

`= 17^3`

_______

\(5^{10}\cdot25\div5^{11}\)

`=`\(5^{10}\cdot5^2\div5^{11}\)

`=`\(5^{10+2-11}\)

`= 5`

_______

\(15^{10}\cdot225\div15^{11}\)

`=`\(15^{10}\cdot15^2\div15^{11}\)

`=`\(15^{12}\div15^{11}\)

`= 15`

`@` `\text {Kaizuu lv uuu}`

\(x^3=125\)

\(\Rightarrow x^3=5^3\)

\(\Rightarrow x=3\)

___________________

\(4^5:4^3\)

\(=4^{5-3}\)

\(=4^2=16\)

___________________

\(8^{12}.8^3:8^{15}\)

\(=8^{15}:8^{15}\)

\(=1\)

___________________

\(7^{15}:7^{13}\)

\(=7^{15-13}\)

\(=7^2=49\)

___________________

\(17^{15}.17^{10}:17^{22}\)

\(=17^{25}:17^{22}\)

\(=17^3=4913\)

___________________

\(5^{10}.25:5^{11}\)

\(=5^{10}.5^2:5^{11}\)

\(=5^{12}:5^{11}\)

\(=5^1=5\)

___________________

\(15^{10}.225:15^{11}\)

\(=15^{10}.15^2:15^{11}\)

\(=15^{12}:15^{11}\)

\(=15^1=15\)

__________________

* aⁿ . a^m = a^n+m

 aⁿ : a^m = a^n-m

Chúc bạn học tốt

\(\dfrac{3}{17}+\dfrac{-8}{15}+\dfrac{-3}{17}+\dfrac{8}{15}+\dfrac{2018}{2019}=\left(\dfrac{3}{17}-\dfrac{3}{17}\right)+\left(\dfrac{8}{15}-\dfrac{8}{15}\right)+\dfrac{2018}{2019}=\dfrac{2018}{2019}\)

\(\dfrac{3}{17}+\dfrac{-8}{15}+\dfrac{-3}{17}+\dfrac{8}{15}+\dfrac{2018}{2019}\)

\(=0+0+\dfrac{2018}{2019}\)

\(=\dfrac{2018}{2019}\)

(-3/17+3/17)+(-8/15+8/15)+2018/2019

0+0+2018/2019

=2018/2019

\(\left(\frac{9}{15}+\frac{8}{11}\right)+\frac{6}{15}=\left(\frac{9}{15}+\frac{6}{15}\right)+\frac{8}{11}\)

\(=1+\frac{8}{11}=\frac{19}{11}\)

\(\left(\frac{26}{17}+\frac{15}{34}\right)+\left(\frac{8}{17}+\frac{19}{34}\right)=\left(\frac{26}{17}+\frac{8}{17}\right)+\left(\frac{15}{34}+\frac{19}{34}\right)\)

\(=2+1=3\)

\(\left(\frac{9}{15}+\frac{8}{11}\right)+\frac{6}{15}\)

\(=\left(\frac{9}{15}+\frac{6}{15}\right)+\frac{8}{11}\)

\(=1+\frac{8}{11}\)

\(=\frac{19}{11}\)

\(\left(\frac{26}{17}+\frac{15}{34}\right)+\left(\frac{8}{17}+\frac{19}{34}\right)\)

\(=\frac{26}{17}+\frac{15}{34}+\frac{8}{17}+\frac{19}{34}\)

\(=\left(\frac{26}{17}+\frac{8}{17}\right)+\left(\frac{15}{34}+\frac{19}{34}\right)\)

\(=2+1\)

\(=3\)

Phương pháp giải:

Trừ nhẩm các số rồi điền kết quả vào chỗ trống.

Lời giải chi tiết:

a)

15 − 6 = 9         15 − 7 = 8

15 − 8 = 7         15 − 9 = 6

16 − 7 = 9         16 − 8 = 8

16 − 9 = 7         17 − 8 = 9

17 − 9 = 8         18 − 9 = 9

b)

18 − 8 − 1 = 9       18 − 9 = 9

15 − 5 − 2 = 8       15 − 7 = 8

16 − 6 − 3 = 7       16 − 9 = 7

15 - 6 = 9, 

15 - 8 =7, 

15 - 7 = 8, 

15 - 9 = 6

`#3107.101107`

\(-16 \div (-8)+5[3-15\div5+2(-3+4)]\)

`= 2 + 5(3 - 3 - 6 + 8)`

`= 2 + 5*(-6 + 8)`

`= 2 + 5*2`

`= 2(5 + 1)`

`= 2*6 = 12`

____

`15*(-236)+15*235`

`= 15 * (-236 + 235)`

`= 15 * (-1)`

`= -15`

____

`237*(-28)+28*137`

`= 28 * (-237 + 137)`

`= 28 * (-100)`

`= -2800`

____

`(-3)*(-17)+3*(120-17)`

`= 3 * 17 + 3 * (120 - 17)`

`= 3 * (17 + 120 - 17)`

`= 3 * 120`

`= 360`

____

`(-8)*72+8*(-19)-(-8)`

`= 8 * (-72) + 8 * (-19) + 8`

`= 8 * (-72 - 19 + 1)`

`= 8 * (-90)`

`= -720`