\(1-\left\{\dfrac{49}{9}+x-\dfrac{113}{18}\right\}:\dfrac{63}{4}=0\)

\(\Leftrightarrow\left\{\dfrac{49}{9}+x-\dfrac{113}{18}\right\}:\dfrac{63}{4}=1\)

\(\Leftrightarrow\dfrac{49}{9}+x-\dfrac{113}{18}=\dfrac{63}{4}\)

\(\Leftrightarrow x-\dfrac{5}{6}=\dfrac{63}{4}\)

\(\Leftrightarrow x=\dfrac{199}{12}\)

`1 - (49/9 + x - 113/18) : 63/4 = 0`

`(49/9 + x - 113/18) : 63/4 =  1-0`

`(49/9 + x - 113/18) : 63/4 = 1`

`49/9 + x - 113/18 = 1 xx 63/4`

`49/9 + x - 113/18 = 63/4`

`(49/9 - 113/18) + x  =63/4`

`-5/6 + x  =63/4`

`x-5/6 = 63/4`

`x=63/4 + 5/6`

`x=189/12 + 10/12`

`x=199/12`

Vậy `x=199/12`

\(\left[\left(8x-12\right):4\right].27=729\)

\(\Leftrightarrow\left(8x-12\right):4=27\)

\(\Leftrightarrow8x-12=108\)

\(\Leftrightarrow8x=120\)

\(\Leftrightarrow x=15\)

x = 15

cứu

\(\dfrac{30\left(x-5\right)}{100}=\dfrac{20x}{100}+5\\ =>\dfrac{30\left(x-5\right)}{100}=\dfrac{20x+500}{100}\\ =>30\left(x-5\right)=20x+500\\ =>30x-150=20x+500\\ =>10x=650\\ =>x=65\)

$\genfrac{}{}{0ex}{}{30\left(x-5\right)}{100}=\genfrac{}{}{0ex}{}{20x}{100}+5=>\genfrac{}{}{0ex}{}{30\left(x-5\right)}{100}=\genfrac{}{}{0ex}{}{20x+500}{100}=>30\left(x-5\right)=20x+500=>30x-150=20x+500=>10x=650=>x=65$

\(4\left(x+1\right)-2x=-2\left(5-x\right)\)

\(\Leftrightarrow4x+4-2x=-10+2x\)

\(\Leftrightarrow2x+4-2x=-10\)

\(\Leftrightarrow0x+4=-10\) ( vô lí )

Vậy không có x thỏa mãn yêu cầu đề bài

\(4\left(x+1\right)-2x=-2\left(5-x\right)\\ =>4x+4-2x=-10+2x\\ =>2x+4=-10+2x\\ =>2x-2x=-4-10\\ =>0=-14=>x\in\varnothing\)

a) \(-x^2+4x+4\)

\(=-\left(x^2-4x-4\right)\)

\(=-\left(x^2-4x+4-8\right)\)

\(=-\left(x-2\right)^2+8\le8\)

Dấu bằng xảy ra \(\Leftrightarrow x-2=0\Leftrightarrow x=2\)

b) \(9x^2-6x+5\)

\(=\left(3x\right)^2-2.3x+1+4\)

\(=\left(3x+1\right)^2+4\ge4\)

Dấu bằng xảy ra \(\Leftrightarrow3x+1=0\Leftrightarrow x=-\dfrac{1}{3}\)

a) 13,45 + 7,98 + 8,55

= (13,45 + 8,55 ) + 7 ,98

= 22 + 7 ,98

= 29,98

b) 9,72 + 8,38 +. 3,62

= 9,72 + 12 

=21,72

c) 7,29 + 9,11 + 0,89

= 7,29 + 10

= 17,29

`13,45 + 7,98 + 8,55`

`=(13,45 + 8,55) + 7,98`

`=22 + 7,98`

`=29,98`

___________________________

`9,72 + 8,38 + 3,62`

`=9,72 +( 8,38 + 3,62)`

`=9,72 + 12`

`=21,72`

___________________________

`7,29 + 9,11 + 0,89`

`=7,29 + (9,11 + 0,89)`

`=7,29 + 10`

`=17,29`