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a: =142*100=14200

b: =436*9-214*100=-17476

c: =78*123=9594

d: =0*A=0

\(a,1337+13\times x=6745\\ \Rightarrow13\times x=6745-1337\\ \Rightarrow x=5408:13\\ \Rightarrow x=416\\ b,142\times x-41\times x-x=408000\\ \Rightarrow x\times\left(142-41-1\right)=408000\\ \Rightarrow x\times100=408000\\ \Rightarrow x=408000:100\\ \Rightarrow x=4080\)

a.      1337 + 13 x x = 6745  

          13 x x            = 6745-1337

           13 x x           = 5408

                     x         = 5408 : 13

                     x         = 416

 b. 142 x x – 41 x x – x = 408000

142 x x – 41 x x – x x 1 = 408000

(142-41-1) x x               = 408 000

100 x x                          = 408000

                x                    = 408 000:100

             x                       = 4080

\(a,\Rightarrow x\times\left(42+54+4\right)=25400\\ \Rightarrow x\times100=25400\\ \Rightarrow x=254\\ b,\Rightarrow x\times\left(142-41-1\right)=40800\\ \Rightarrow x\times100=40800\\ \Rightarrow x=408\)

a) \(x\)(42+54+4)=15400            b) (142-41-1)\(x\)=10800
\(x\)x100=15400                             100x\(x\)=10800
\(x\)=15400:100                                      \(x\)=10800:100
\(x\)=154                                                 \(x\)=108

a) y x 42 + y x 57 + y = 25 400

y x ( 42 + 57 + 1 ) = 25 400

y x 100 = 25 400

y = 25 400 : 100

y = 254

b) 142 x y - 41 x y - y = 408 000

y x ( 142 - 41 - 1 ) = 408 000

y x 100 = 408 000

y = 408 000 : 100

y = 4 080

a.y*(42+57+1)=25400

y*100=25400

y=25400:100=254

b.(142-41-1)*y=408000

100*y=408000

y=408000:100=4080

a: \(280-\left(x-140\right):35=270\)

=>(x-140):35=280-270=10

=>x-140=350

=>x=350+140

=>x=490

b: \(\left(190-2x\right):35-32=16\)

=>\(\left(190-2x\right):35=32+16=48\)

=>\(190-2x=35\cdot48=1680\)

=>2x=190-1680=-1490

=>x=-745

c: \(720:\left\lbrack41-\left(2x-5\right)\right\rbrack=2^3\cdot5\)

=>\(720:\left\lbrack41-\left(2x-5\right)\right\rbrack=8\cdot5=40\)

=>41-(2x-5)=720:40=18

=>2x-5=41-18=23

=>2x=28

=>x=14

d: \(\left(x:23+45\right)\cdot37-22=2^4\cdot105\)

=>\(\left(\frac{x}{23}+45\right)\cdot37=16\cdot105+22=1702\)

=>\(\frac{x}{23}+45=46\)

=>\(\frac{x}{23}=1\)

=>x=23

e: \(\left(3x-4\right)\left(x-1\right)^3=0\)

=>\(\left[\begin{array}{l}3x-4=0\\ x-1=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\frac43\\ x=1\end{array}\right.\)

f: \(2^{2x-1}:4=8^3\)

=>\(2^{2x-1-2}=2^9\)

=>2x-3=9

=>2x=12

=>x=6

g: \(x^{17}=x\)

=>\(x^{17}-x=0\)

=>\(x\left(x^{16}-1\right)=0\)

=>\(\left[\begin{array}{l}x=0\\ x^{16}-1=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=0\\ x^{16}=1\end{array}\right.\Rightarrow\left[\begin{array}{l}x=0\\ x=1\\ x=-1\end{array}\right.\)

h: \(\left(x-5\right)^4=\left(x-5\right)^6\)

=>\(\left(x-5\right)^6-\left(x-5\right)^4=0\)

=>\(\left(x-5\right)^4\cdot\left\lbrack\left(x-5\right)^2-1\right\rbrack=0\)

=>\(\left(x-5\right)^4\cdot\left(x-4\right)\left(x-6\right)=0\)

=>x∈{4;5;6}

i: \(\left(x+2\right)^5=2^{10}\)

=>\(\left(x+2\right)^5=\left(2^2\right)^5=4^5\)

=>x+2=4

=>x=2

k: 1+2+3+...+x=78

=>\(\frac{x\left(x+1\right)}{2}=78\)

=>x(x+1)=156

=>\(x^2+x-156=0\)

=>(x+13)(x-12)=0

=>x=-13(loại) hoặc x=12(nhận)

l: \(\left(3x-2^4\right)\cdot7^3=2\cdot7^4\)

=>\(3x-16=2\cdot\frac{7^4}{7^3}=2\cdot7=14\)

=>3x=16+14=30

=>\(x=\frac{30}{3}=10\)

n: \(5^{x}:5^2=125\)

=>\(5^{x-2}=5^3\)

=>x-2=3

=>x=5

m: \(\left(x+1\right)^2=\left(x+1\right)^0\)

=>\(\left(x+1\right)^2=1\)

=>\(\left[\begin{array}{l}x+1=1\\ x+1=-1\end{array}\right.\Rightarrow\left[\begin{array}{l}x=0\\ x=-2\end{array}\right.\)

o: Số số hạng của dãy số 2;4;..;52 là:

(52-2):2+1=50:2+1=25+1=26(số)

Tổng của dãy số 2;4;...;52 là:

\(\left(52+2\right)\cdot\frac{26}{2}=54\cdot13=702\)

(2+x)+(4+x)+...+(52+x)=780

=>26x+702=780

=>26x=78

=>x=3

p: \(70=2\cdot5\cdot7;80=2^4\cdot5\)

=>ƯCLN(70;80)=\(2\cdot5=10\)

70⋮x; 80⋮x

=>x∈ƯC(70;80)

=>x∈Ư(10)

mà x>8

nên x=10

q: \(12=2^2\cdot3;25=5^2;30=2\cdot3\cdot5\)

=>BCNN(12;25;30)=\(2^2\cdot3\cdot5^2=300\)

x⋮12; x⋮25; x⋮30

=>x∈BC(12;25;30)

=>x∈B(300)

mà 0<x<500

nên x=300

các bn ơi giải hộ mk đi

a, 41 x 42 x 43 x 44 x 45 x 46 x 47 x 48 x 49 

Ta có : 44 x 45 có CSTC la` 0 vi` 4 x 5 = 2

=> 41 x 42 x 43 x ... x 49 co' CSTC la` 0

b, 69 x 31 x 35 x 37 - 24 x 17 x 35 x 14

= ( ...5) - ( ..0 ) = (...5)

142 . x - 41 .x - x = 800000

( 142 - 41 - 1 ) . x = 800000

100 . x = 800000

x = 8000

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LÀM ƠN!

a ) x = 1 9 + 5 7 = 52 63 b ) x = 2 15 − 3 10 = − 1 6

c ) x = 2 45 − 1 9 = − 1 15 ; d ) x = − 3 7 − 4 5 − − 2 3 = − 59 105