a) 4,6,8,10,12

B)5,10,15,20,25

a) 4,6,8,10,12

B)5,10,15,20,25

Ta có x < 19,54 < y

\(\Rightarrow x=19,y=20\)

x = 19 

y = 20

\(xy+2x+2y=-16\)

\(\Rightarrow x\left(y+2\right)+2y+4-4=-16\)

\(\Rightarrow x\left(y+2\right)+2\left(y+2\right)=-12\)

\(\Rightarrow\left(y+2\right)\left(x+2\right)=-12\)

\(\Rightarrow\left(x+2\right);\left(y+2\right)\in B\left(12\right)=\left\{-1;1;-2;2;-3;3;-4;4;-6;6;-12;12\right\}\)

\(\Rightarrow\left(x;y\right)\in=\left\{\left(-3;10\right);\left(-1;-14\right);\left(-4;3\right);\left(0;-8\right);\left(-5;2\right);\left(1;2\right);\left(-6;1\right);\left(2;-5\right);\left(-8;0\right);\left(4;-4\right);\left(-14'-1\right);\left(10;-3\right)\right\}\)

\(\left(x+2\right);\left(y+2\right)\) không phải thuộc B(12) mà nó phải là 2 số nguyên có tích bằng 12 chứ em

`2^x :4=8`

`2^x =8xx4`

`2^x =32`

`2^x =2^5`

`=>x=5`

\(2^x:4=8\\ \Rightarrow2^x=32\\ \Rightarrow2^x=2^5\)

\(\Rightarrow x=5\)

1. (Mình đưa nó về thừa số nguyên tố nha, cái nào ko đc thì thôi)

125 = 5³; 27 = 3³; 64 = 2⁶; 1296 = 6⁴; 1024 = 2¹⁰; 2401 = 7⁴; 4³ = 64; 8 = 2³; 25.125 = 3125 = 5⁵.

2.

2ⁿ = 16 =) n = 4.           3ⁿ = 81 =) n = 4.      2^n-1 = 64 =) n = 7.        3ⁿ⁺² = 27.81 =) n = 5.       25.5^n-1 = 625 =) n = 3.

2ⁿ.8 = 128 =) n = 4.     3.5ⁿ = 375 =) n = 3.   (3ⁿ)² = 729 =) n = 3.        81 ≤ 3ⁿ ≤ 729 =) n = 4; 5; 6.

\(125=5^3;27=3^3;1296=36^2=6^4=2^4.3^4;1024=32^2=2^{10};2401=49^2=7^4;4^3=2^6;8=2^3;25.125=5^2.5^3=5^5\)

\(10x+2^2.5=10^2\)

\(10x+4.5=100\)

\(10x+20=100\)

\(10x=100-20\)

\(10x=80\)

\(x=80:10\)

\(x=8\)

x = 8

\(4^n=256\Rightarrow4^n=4^4\Rightarrow x=4\)

n=256⇒4n=44⇒x=4

\(Vìx^{849}=1\Rightarrow x=1hoặcx=0.\)

\(x^{849}=1\)

\(\Rightarrow x=1\)

\(\Rightarrow x=-1\)

Vì \(1^{849}=1\)

\(\left(-1\right)^{849}=1\)

`1,`

`538 - x = 275`

`\Rightarrow x = 538 - 275`

`\Rightarrow x = 263`

Vậy, `x = 263`

`2,`

`45 - 9x = 18`

`\Rightarrow 9x = 45 - 18`

`\Rightarrow 9x = 27`

`\Rightarrow x = 27 \div 9`

`\Rightarrow x = 3`

Vậy, `x = 3`

`3,`

`(5x - 9) \div 3 = 12`

`\Rightarrow 5x - 9 = 12. 3`

`\Rightarrow 5x - 9 = 36`

`\Rightarrow 5x = 36 + 9`

`\Rightarrow 5x = 45`

`\Rightarrow x = 45 \div 5`

`\Rightarrow x = 9`

Vậy, `x = 9.`

1) \(538-x=275\)

\(x=538-275\)

\(x=263\)

2) \(45-9x=18\)

\(9x=27\)

\(x=3\)

3) \(\left(5x-9\right)\div3=12\)

\(\left(5x-9\right)=12\times3\)

\(5x-9=36\)

\(5x=45\)

\(x=9\)