`#` `\text{dkhanhqlv}`

`4)`

`a)3.(-5/11)`

`=-15/11`

`b)3/5+4/7 . 14/6`

`=3/5 + 4/3`

`=9/15+20/15`

`=29/15`

`c) 10/21-3/8 . 4/15`

`=10/21-1/10`

`=100/210-21/210`

`=79/100`

`d)(2/3+3/4)(5/7+5/14)`

`=(8/12+9/12)(10/14+5/14)`

`=17/12 . 15/14`

`=85/56`

`5)`

`a)x-1/2=3/10 . 5/6`

`=>x-1/2=1/4`

`=>x=1/4+1/2`

`=>x=1/4+2/4`

`=>x=3/4`

`b)x/5 = -3/14`

`=>x : 5 = -3/14`

`=>x=-3/14 . 5`

`=>x=-15/14`

`c)x+2/3=9/15 . 5/27`

`=>x+2/3=1/9`

`=>x=1/9-2/3`

`=>x=1/9-6/9`

`=>x=-5/9`

Câu 1 xem kỉ đề

\(B,\frac{49^6.5-7^{11}}{\left(-7\right)^{10}.5-2.49^5}=\frac{7^{12}.5-7^{11}}{7^{10}.5-2.7^{10}}=\frac{7^{11}.\left(7.5-1\right)}{7^{10}.\left(5-2\right)}=\frac{7.34}{3}=\frac{238}{3}\)

a) A=2¹².3⁵-\(\frac{2^{12}.3^6}{2^{12}}\)+9³+8⁴.3⁵

=2¹².3⁵-3⁶+3⁶+2¹².3⁵

=2¹³.3⁵

^b)B=49⁶.5-5.\(\frac{7^{11}}{\left(-7\right)^{10}}-2.49^5\)

=49⁶.5-7.5-2.49⁵

⁼7¹².5-7.5-2.7¹⁰

y x 11 - y = 10.5

y x ( 11 - 1 ) = 10.5

y x 10 = 10.5

y = 10.5 : 10

y = 1.05

Bn ơi, đầu bài là 10,5 hay 10x5 thế

10,5 nha bn

\(\dfrac{45^{10}.5^{20}}{75^{15}}\)

\(=\dfrac{9^{10}.5^{10}.5^{20}}{25^{15}.3^{15}}\)

\(=\dfrac{3^{20}.5^{30}}{5^{30}.3^{15}}\)

\(=3^5=243\)

Ta có: \(\frac{45^{10}\cdot5^{20}}{75^{15}}\)

\(=\frac{15^{10}\cdot3^{10}\cdot5^{20}}{15^{15}\cdot5^{15}}=\frac{15^{10}\cdot3^{10}}{15^{10}\cdot15^5}\cdot3125=\frac{3^{10}\cdot5^5}{3^5\cdot5^5}=\frac{3^{10}}{3^5}=243\)