13 - 2(x + 1) = 7

=> 2(x + 1) = 13 - 7 = 6

=> (x + 1) = 6 : 2 = 3 

=> x = 2

6x + 2³ = 5². 2

=> 6x + 8 = 25. 2

=> 6x + 8 = 50

=> 6x = 50 - 8 = 42

=> x = 7

x + 2 . x + 3x + .... + 9x = 450 

x.(1+ 2 + 3 + ... + 9) = 450

x. 45 = 450 

=> x = 450 : 45 = 10

1) 13-2(x+1)=7

<=>2(x+1)=6

<=>x+1=3

<=>x=2

2) 6x+2³=5².2

<=>6x=42

<=>x=7

3) 420+56.4=(x+175):5+30

<=>644-30=(x+175):5

<=>614x5=x+175

<=>3070-175=x

<=>x=2895

4) x+2x+3x+...+9x=450

<=>x(1+2+3+...+9)=450

<=>45x=450

<=>x=10

$a)(x-25)-175=0$

$\to x-25=0+175=175$

$\to x=175+25$

$\to x=200$

$b)485-(6.x+60)=5$

$\to 6.x+60=485-5=480$

$\to 6.x=480-60=420$

$\to x=420:6=70$

c) ( x - 31 ) - 68 = 0

x - 31 - 68 = 0

x - 99 = 0

x - 99 +99 = 0 + 99

x = 0 + 99

x = 99

\(1) 420+65.4=(x+175):5+30\)

\(\implies 420+260=(x+175):5+30\)

\(\implies 680=(x+175):5+30\)

\(\implies 650=(x+175):5\)

\(\implies 650.5-175=x\)

\(\implies 3075=x\)

\(2)x-4867=(175.2050.70):25+23\)

\(\implies x-4867=1004500+23\)

\(\implies x-4867=1004523\)

\(\implies x=1009390\)

\(3) 134-[(96-7x):4-2]=126\)

\(\implies (96-7x):4-2=8\)

\(\implies(96-7x):4=10\)

\(\implies 96-7x=40\)

\(\implies 7x=56\)

\(\implies x=8\)

\(4) 4-\{100-[(100-5x):8-5]:10\}:25=0\)

\(\implies 4-\{100-[(100-5x):8-5]:10\}=0\)

\(\implies 100-[(100-5x):8-5]:10=4\)

\(\implies 100-[(100-5x):8-5]=40\)

\(\implies (100-5x):8-5=60\)

\(\implies (100-5x):8=65\)

\(\implies 100-5x=520\)

\(\implies 5x=-420\)

\(\implies x=-84\)

~ Hok tốt a~

ai nua cac ban

ban nao biet thi minh h

\(a,\Rightarrow6x+70=130\Rightarrow6x=60\Rightarrow x=10\\ b,\Rightarrow240=\left(x+70\right):14-40\\ \Rightarrow\left(x+70\right):14=280\\ \Rightarrow x+70=3920\Rightarrow x=3850\\ c,\Rightarrow x-15=75\Rightarrow x=90\\ d,\Rightarrow\left(x+175\right):5=680-30=650\\ \Rightarrow x+175=3250\Rightarrow x=3075\\ e,\Rightarrow x-4867=1004523\Rightarrow x=1009390\\ f,\Rightarrow x+32-17=24\Rightarrow x=9\\ g,\Rightarrow3\left(x+1\right)=54\Rightarrow x+1=18\Rightarrow x=17\\ h,\Rightarrow19\left(35:x+3\right)=152\\ \Rightarrow35:x+3=8\Rightarrow35:x=11\Rightarrow x=\dfrac{35}{11}\)

Áp dụng định lý Bê-du, ta có :

Khi \(P\left(x\right)\)chia hết cho \(x-2\Rightarrow P\left(2\right)=0\)

\(\Rightarrow6.2^5+a.2^4+b.2^3+2^2+c.2+450=0\)

\(\Rightarrow192+16a+8b+4+2c+450=0\)

\(\Rightarrow16a+8b+2c=-646\)

\(\Rightarrow8a+4b+c=-323\)

Khi \(P\left(x\right)\)chia hết cho \(x-3\Rightarrow P\left(3\right)=0\)

\(\Rightarrow P\left(3\right)=6.3^5+a.3^4+b.3^3+3^2+3c+450=0\)

\(\Rightarrow1458+81a+27b+9+3c+450=0\)

\(\Rightarrow81a+27b+3c=-1917\)

\(\Rightarrow27a+9b+c=-639\)

Khi \(P\left(x\right)\)chia hết cho \(x-5\Rightarrow P\left(5\right)=0\)

Làm tương tự, có :

\(125a+25b+c=-3845\)

Bạn tự xét phần tiếp theo vì ở đây đã có 3 dữ kiện để tìm a, b , c rồi.

{2;5}

x thuộc ƯC(280,700,420)

=>x={70}

a,      x=(-18):(-6)=3

b,       x+7=(-15):(-5)=3

        => x = 3-7= -4

a) x = 3

b) bấm máy 

a)x=3

b)x=-4

thế này mới đúng

a) x = 160

b) x = 5

c) x = 107

d) x = 3