a) 125 - 5(x + 10) = 12
=> 5(x + 10) = 125 - 12 = 113
=> x + 10 = 113 : 5
=> x + 10 = 113/5
=> x = 113/5 - 10 = 63/5
b) (x - 1)2 = 4 => (x - 1)2 = (\(\pm\)2)2
=> x - 1 = 2 hoặc x - 1 = -2
=> x = 3 hoặc x = -1
c) 5x+1 - 52 . 17 = 52.8
=> 5x . 5 - 52 . 17 = 52 . 8
=> 5x . 5 = 52.8 + 52 . 17
=> 5x . 5 = 52(8 + 17)
=> 5x . 5 = 52 . 52
=> 5x = \(\frac{5^2\cdot5^2}{5}=5^3\)
=> x = 3
d) 84 + (12 - 3.x) : 6 = 85
=> 84 + (12 - 3.x) = 510
=> 12 - 3.x = 426
=> 3.x = -414
=> x = -138
e) (x + 1) + (x + 2) + (x + 3) + ... + (x + 99) + (x + 100) = 5150
=> x + 1 + x + 2 + x + 3 + ... + x + 99 + x + 100 = 5150
=> (x + x + .... + x) + (1 + 2 + 3+ ... + 100) = 5150
=> 100x + 5050 = 5150
=> 100x = 5150 - 5050 = 100
=> x = 1
Bài làm:
\(a,125-5.\left(x+10\right)=12\)
\(\Rightarrow5.\left(x+10\right)=125-12\)
\(\Rightarrow5.\left(x+10\right)=113\)
\(\Rightarrow x+10=\frac{113}{5}\)
\(\Rightarrow x=\frac{63}{5}\)
\(b,\left(x-1\right)^2=4\)
\(\Rightarrow\left(x-1\right)^2=2^2\)
\(\Rightarrow\orbr{\begin{cases}x-1=2\\x-1=-2\end{cases}}\Rightarrow\orbr{\begin{cases}x=3\\x=-1\end{cases}}\)
\(c,5^{x+1}-5^2.17=5^2.8\)
\(\Rightarrow5^{x+1}-425=200\)
\(\Rightarrow5^{x+1}=200+425\)
\(\Rightarrow5^{x+1}=625\)
\(\Rightarrow5^{x+1}=5^4\)
\(\Rightarrow x+1=4\)
\(\Rightarrow x=3\)
\(d,84+\left(12-3.x\right):6=85\)
\(\left(12-3x\right):6=85-84\)
\(\left(12-3x\right):6=1\)
\(12-3x=6\)
\(3x=6\)
\(x=2\)
\(e,\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+99\right)+\left(x+100\right)=5150\)
\(100.x+\left(1+2+3+...+99+100\right)=5150\)
\(100.x+5050=5150\)
\(100.x=5150-5050\)
\(100.x=100\)
\(x=1\)
Học tốt nhé
Sửa lại câu d nhaa , xin lỗi bạn nhé
84 + (12 - 3x) : 6 = 85
=> (12 - 3x) : 6 = 85 - 84
=> (12 - 3x) : 6 = 1
=> 12 - 3x = 6
=> 3x = 6
=> x = 2
a) 125 - 5(x + 10) = 12
=> 5(x + 10) = 125 - 12 = 113
=> x + 10 = 113 : 5
= 113/5
=> x = 113/5 - 10 = 63/5
b) (x - 1) 2 = 4 => (x - 1) 2 = \(\left(\ne2\right)^2\)
=> x - 1 = 2 hoặc x - 1 = -2
=> x = 3 hoặc x = -1
c) 5 x+1 - 5 2 . 17 = 5 2 .8
=> 5 x . 5 - 5 2 . 17 = 5 2 . 8
=> 5 x . 5 = 5 2 .8 + 5 2 . 17
=> 5 x . 5 = 5 2(8 + 17)
=> 5 x . 5 = 5 2 . 5 2
=> 5 x =\(\frac{5^2.5^2}{5}=5^3\)
d,84 + (12 - 3x) : 6 = 85
=> (12 - 3x) : 6 = 85 - 84
=> (12 - 3x) : 6 = 1
=> 12 - 3x = 6
=> 3x = 6
=> x = 2
e) (x + 1) + (x + 2) + (x + 3) + ... + (x + 99) + (x + 100) = 5150
=> x + 1 + x + 2 + x + 3 + ... + x + 99 + x + 100 = 5150
=> (x + x + .... + x) + (1 + 2 + 3+ ... + 100) = 5150
=> 100x + 5050 = 5150
=> 100x = 5150 - 5050 = 100
=> x = 1
