5x+1 - 5x = 100.2529
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A = (5\(x\) + 1)2 + (5\(x\) - 1)2 - 2.( 5\(x\) +1).(5\(x\) - 1) tại \(x\) = 1
Thay \(x\) = 1 vào A ta có:
A = (5.1 + 1)2 + (5.1 - 1)2 - 2.(5.1 + 1).(5.1 - 1)
A = 62 + 42 - 2.6.4
A = 36 + 16 - 48
A = 52 - 48
A = 4
\(\left(5x-1\right)^2+2\left(1-5x\right)\left(4+5x\right)+\left(5x+4\right)^2\)
\(=\left(5x-1\right)^2-2\left(5x-1\right)\left(5x+4\right)+\left(5x+4\right)^2\)
\(=\left[\left(5x-1\right)-\left(5x+4\right)\right]^2\)
\(=\left(5x-1-5x-4\right)^2\)
\(=\left(-5\right)^2\)
\(=25\)
\(\dfrac{3}{{5x - 1}} + \dfrac{2}{{3 - 5x}} = \dfrac{4}{{\left( {1 - 5x} \right)\left( {x - 3} \right)}}\)
ĐKXĐ: \(x \ne \dfrac{1}{5};x\ne \dfrac{3}{5};x \ne 3\)
\( \Leftrightarrow 3\left( {3 - 5x} \right)\left( {x - 3} \right) + 2\left( {5x - 1} \right)\left( {x - 3} \right) + 4\left( {3 - 5x} \right) = 0\\ \Leftrightarrow 9x - 27 - 15{x^2} + 45x + 10{x^2} - 30x - 2x + 6 + 12 - 20x = 0\\ \Leftrightarrow - 5{x^2} + 2x - 9 = 0 \)
\(\Rightarrow\) Phương trình vô nghiệm.
\(5^x+5^{x+1}+5^{x+2}+5^{x+3}=1+2+3+...+87+88-4^2\)
=>\(5^x+5^x\cdot5+5^x\cdot25+5^x\cdot125=88\cdot\dfrac{\left(88+1\right)}{2}-16\)
=>\(156\cdot5^x=44\cdot89-16=3900\)
=>\(5^x=\dfrac{3900}{156}=25\)
=>x=2
P = (5x − 1) + 2(1 − 5x)(4 + 5x) + 5 x + 4 2
= 5x – 1 + (2 – 10x).( 4+ 5x) + 5 x + 4 2
= 5x – 1 + 8 + 10x – 40x – 50 x 2 + 25 x 2 + 40x + 16
= (- 50 x 2 + 25 x 2 )+ ( 5x + 10x – 40x + 40x) + (- 1+ 8 + 16)
= -25 x 2 + 15x + 23
Lời giải:
Tại $x=4$ thì:
\(A=5(x^5-x^4+x^3-x^2+x-1)-1\)
\(=(x+1)(x^5-x^4+x^3-x^2+x-1)-1=x^6+1-1=x^6\)
\(=4^6=4096\)
\(5^{x+1}-5^x=100\cdot25^{29}\)
\(\Rightarrow5^x\left(5-1\right)=100\cdot\left(5^2\right)^{29}\)
\(\Rightarrow5^x\cdot4=100\cdot5^{58}\)
\(\Rightarrow5^x=\dfrac{100\cdot5^{58}}{4}\)
\(\Rightarrow5^x=25\cdot5^{58}\)
\(\Rightarrow5^x=5^{60}\)
\(\Rightarrow x=60\)
\(5^{x+1}-5x=100.25^{29}\)
\(5.5^x-5^x=4.25.25^{29}\)
\(5^x.\left(5-1\right)4.25^{30}\)
\(4.5^x-4.\left(5^2\right)^{30}\)
\(5x=5^{60}\)
\(x=60\)