a) 89-(73-x)=20

=>73-x=89-20

=>73-x=69

=>x=73-69

=>x=4

A . 89 - ( 73 - x ) = 20

              73 - x   = 89 - 20

              73 - x   = 69

              \(\Rightarrow\)x = 4

B .

  Bài 1:

2^\(x\) = 4

2\(^x\) = 2²

 \(x=2\)

Vậy \(x=2\)

Bài 2:

2\(^x\) = 8

2\(^x\) = 2³

\(x=3\)

Vậy \(x=3\)

Bài 1:

\(555-5\cdot\left\lbrack409-\left(2^3\cdot3-21\right)^2-310\right\rbrack\)

\(=555-5\cdot\left\lbrack409-\left(8\cdot3-21\right)^2-310\right\rbrack\)

\(=555-5\cdot\left\lbrack409-3^2-310\right\rbrack=555-5\cdot\left(400-310\right)=555-5\cdot90\)

=555-450

=105

Bài 2:

a: \(10x+187=617^{10}:617^9\)

=>10x+187=617

=>10x=617-187=430

=>\(x=\frac{430}{10}=43\)

b: \(5^{x+2}=25^4\)

=>\(5^{x+2}=\left(5^2\right)^4=5^8\)

=>x+2=8

=>x=8-2=6

c: 2x+17⋮x+4

=>2x+8+9⋮x+4

=>9⋮x+4

=>x+4∈{1;-1;3;-3;9;-9}

=>x∈{-3;-5;-1;-7;5;-13}

vip đây

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nhiều thê

sbn gủi từng câu

một thôi thì

trả lời dễ hơn đó

thôi kệ mình lỡ rồi bạn giúp mình nhé

a. x mũ 2 - 2x + 1 = 25 

= x^2 + 2.x.1 + 1^2

= ( x + 1 ) ^2

ko bt có đúng ko nữa, mấy câu kia tui ko bt lm

Sos

Bài 1 :

\(M=\dfrac{30-2^{20}}{2^{18}}=\dfrac{2.15-2^{20}}{2^{18}}=\dfrac{15}{2^{17}}-2^2=\dfrac{15}{2^{17}}-4< 0\left(\dfrac{15}{2^{17}}< 1\right)\)

\(N=\dfrac{3^5}{1^{2021}+2^3}=\dfrac{3^5}{9}=\dfrac{3^5}{3^2}=3^3=27\)

\(\Rightarrow M< N\)

Bài 3 :

a) \(t^2+5t-8\) khi \(t=2\)

\(=5^2+2.5-8\)

\(=25+10-8\)

\(=27\)

b) \(\left(a+b\right)^2-\left(b-a\right)^3+2021\left(1\right)\)

\(\left\{{}\begin{matrix}a=5\\b=a+1=6\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}a+b=11\\b-a=1\end{matrix}\right.\)

\(\left(1\right)=11^2-1^3+2021=121-1+2021=2141\)

c) \(x^3-3x^2y+3xy^2-y^3=\left(x-y\right)^3\left(1\right)\)

\(\left\{{}\begin{matrix}x=3\\y=2\end{matrix}\right.\) \(\Rightarrow x-y=1\)

\(\left(1\right)=1^3=1\)

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