a) 450 – ( 25 – 10) = 450 – 15

                   = 435

450 – 25 – 10 = 425 – 10

                   = 415

b) 180 : 6 : 2 = 30 : 6

                   = 15

180 : ( 6 : 2 ) = 180 : 3

                   = 60

c) 410 – (50 +30) = 410 -80

                   = 330

410 - 50 + 30 = 360 + 30

                   = 390

d) 16 x (6 : 3) = 16 x 2

                   = 32

16 x 6 : 3 = 96 : 3

                   = 32

\(54\times450+18\times126\times3+848\times27\)

\(=54\times450+\left(18\times3\right)\times126+\left(27\times2\right)\times424\)

\(=54\times450+54\times126+54\times424\)

\(=54\times\left(450+126+424\right)\)

\(=54\times\left(450+550\right)\)

\(=54\times1000\)

\(=54000\)

54000

a) x  -1/4 = -3/8 . 2/5

    x - 1/4 = -3/20

    x        = -3/20 + 1/4

    x        = 1/10

b) x/126 = -7/24 . -6/11

    x/126 = 7/44

\(\Rightarrow\)x = rỗng

a, x- 1/4 = (-3/20) 
   x= 1/10

b, x/126 = (7/44)
    x = 441/22

426 :2 + 34:x = 5

213 + 34:x =5

34:x= -208

x= -17/104

360 : x-126:x = 6

(360- 126) :x = 6

234 :x =6

x= 39

(Bạn xem lại câu a nhé, lớp 4 chưa học số âm)

426 : 2+34: x=5

213 + 34 : x =  5

247 : x = 5

x = 247 : 5 

x = 49.4 

360:x-126:x=6

( 360 - 126 ) : x = 6

234 : x = 6

x = 234 : 6

x = 39

a) 426:2+34:x=5

=> 213 -5=34:x

=> x=34: 208

=> x= \(\frac{17}{104}\)

b) 360:x-126:x=6

=> (360-126):x=6

=> x= 234:6

=> x= 39

Bài 2: 

a: =>x-45=-20

hay x=25

b: =>35+30-5x=-12+112

=>65-5x=100

=>5x=-35

hay x=-7

c: =>x-124=1000

hay x=1124

d: \(\Leftrightarrow46-\left(3x-2\right)^3=-18\)

\(\Leftrightarrow\left(3x-2\right)^3=64\)

=>3x-2=4

hay x=2

Bài 2: 

a: =>x-45=-20

hay x=25

b: =>35+30-5x=-12+112=100

=>65-5x=100

=>5x=-35

hay x=-7

c: =>x-124=1000

hay x=1124

d: \(\Leftrightarrow46-\left(3x-2\right)^3=-18\)

\(\Leftrightarrow\left(3x-2\right)^3=64\)

=>3x-2=4

hay x=2

Bài 1.

\(a,\left(2^4\cdot3\cdot5^2\right):\left\{450:\left[450-\left(4\cdot5^3-2^3\cdot5^2\right)\right]\right\}\)

\(=\left(16\cdot3\cdot25\right):\left\{450:\left[450- \left(4\cdot125-8\cdot25\right)\right]\right\}\)

\(=\left(48\cdot25\right):\left\{450:\left[450-\left(500-200\right)\right]\right\}\)

\(=1200:\left[450:\left(450-300\right)\right]\)

\(=1200:\left(450:150\right)\)

\(=1200:3\)

\(=400\)

\(---\)

\(b,3^3\cdot5^2-20\left\{90-\left[164-2\cdot\left(7^8:7^6+7^0\right)\right]\right\}\)

\(=27\cdot25-20\left\{90-\left[164-2\cdot\left(7^2+1\right)\right]\right\}\)

\(=675-20\left\{90-\left[164-2\cdot\left(49+1\right)\right]\right\}\)

\(=675-20\left[90-\left(164-2\cdot50\right)\right]\)

\(=675-20\left[90-\left(164-100\right)\right]\)

\(=675-20\left(90-64\right)\)

\(=675-20\cdot26\)

\(=675-520\)

\(=155\)

\(---\)

\(c,\left[\left(18^7:18^6-17\right)\cdot2022-1986\right]\cdot5\cdot1^{2022}-13^2\cdot2020^0\)

\(=\left[\left(18-17\right)\cdot2022-1986\right]\cdot5\cdot1-169\cdot1\)

\(=\left(1\cdot2022-1986\right)\cdot5-169\)

\(=\left(2022-1986\right)\cdot5-169\)

\(=36\cdot5-169\)

\(=180-169\)

\(=11\)

Bài 2.

\(a) (2^x+1)^2+3\cdot(2^2+1)=2^2\cdot10\\\Rightarrow (2^x+1)^2+3\cdot(4+1)=4\cdot10\\\Rightarrow (2^x+1)^2+3\cdot5=40\\\Rightarrow (2^x+1)^2+15=40\\\Rightarrow (2^x+1)^2=40-15\\\Rightarrow (2^x+1)^2=25\\\Rightarrow (2^x+1)^2= (\pm 5)^2\\\Rightarrow \left[\begin{array}{} 2^x+1=5\\ 2^x+1=-5 \end{array} \right.\\ \Rightarrow \left[\begin{array}{} 2^x=4\\ 2^x=-6 (vô.lí) \end{array} \right. \\ \Rightarrow 2^x=2^2\\\Rightarrow x=2\)

Vậy \(x=2\).

\(---\)

\(b)3\cdot(x-7)+2\cdot(x+5)=41\\\Rightarrow 3\cdot x+3\cdot(-7)+2\cdot x+2\cdot5=41\\\Rightarrow 3x-21+2x+10=41\\\Rightarrow (3x+2x)+(-21+10)=41\\\Rightarrow 5x-11=41\\\Rightarrow 5x=41+11\\\Rightarrow 5x=52\\\Rightarrow x=\dfrac{52}{5}\)

Vậy \(x=\dfrac{52}{5}\).

\(Toru\)

a) 246 : x + 34 : x = 5

    ( 246 + 34 ) : x = 5

            280 : x     = 5

                     x     = 280 : 5

                     x     =  56

b) 360 : x - 126 : x = 6

    ( 360 - 126 ) : x = 6

.               234   : x = 6

                           x = 234 : 6

                           x = 39

a, 246 : x + 34 : x = 5

    ( 246 + 34 ) : x  = 5

          280  : x       = 5

                          x = 280 : 5

                          x = 56

                     Vay x=56 

b , 360 : x - 126 : x = 6

      ( 360 - 126 ) : x = 6

                     234 : x= 6   

                              x= 234 : 6

                              x= 39

                        Vay x=39

246 : x + 34 : x = 5

( 246 + 34 ) : x = 5

       280 : x = 5

        x = 280 : 5

        x =  56

360 : x - 126 : x = 6

( 360 - 126 ) : x = 6

    234 : x = 6

    x = 234 : 6

    x = 39