tìm x biết 2x+2 . 3x+1.5x = 10800
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`2^(x+2) . 3^(x+1) . 5^x = 10800`
`=> 2^x. 2^2. 3^x. 3. 5^x=10800`
`=> (2.3.5)^x. (4.3)=10800`
`=> 30^x. 12=10800`
`=> 30^x=10800:12`
`=> 30^x=900`
`=> 30^x=30^2`
`=> x=2`
\(a,121-\left(115+x\right)=3x-\left(25-9-5x\right)-8\\ 121-115-x=3x-25+9+5x-8\\ 6-x=8x-24\\ 8x+x=-24-6\\ 9x=-30\\ x=-\dfrac{30}{9}=-\dfrac{10}{3}\\ ----\\ b,2^{x+2}.3^{x+1}.5^x=10800\\ \left(2.3.5\right)^x.2^2.3=10800\\ 30^x.12=10800\\ 30^x=\dfrac{10800}{12}=900=30^2\\ Vậy:x=2\)
- 2(x+5)(x-5)-(x+2)(2x-3)+x(x^2-8)=(x+1)(x^2-x+1)
<=> 2(x^2-25) - 2x^2+3x-4x+6 + x^3-8x = x^3+1
=>2x^2-50 - 2x^2 -9x+6+x^3-x^3-1 = 0
<=>-9x - 45 =0
<=>-9x=45
<=>x=-5
Còn phần b và c bạn cứ khai triển ra,mình phải đi học nên không có thời gian giải cho bạn
Tìm x biết :
a) 3(5/3x-7)-2(1.5x+6)-(5-x)(x+4)=80+x^2
b) 4/5x^2(x/3-1/2)-(1/5x-2/3)(4x^2/3+1)=22/45x^2
`Answer:`
\(3\left(\frac{5}{3}x-7\right)-2\left(1.5x+6\right)-\left(5-x\right)\left(x+4\right)=80+x^2\)
\(\Leftrightarrow3\left(\frac{5x}{3}-7\right)-2\left(5x+6\right)-\left(5-x\right)\left(x+4\right)=80+x^2\)
\(\Leftrightarrow5x-21-10x-12-5x-20+x^2+4x=80+x^2\)
\(\Leftrightarrow5x-21-10x-12-5x-20+4x=80\)
\(\Leftrightarrow-6x-53=80\)
\(\Leftrightarrow-6x=133\)
\(\Leftrightarrow x=-\frac{133}{6}\)
\(\frac{4}{5}x^2\left(\frac{x}{3}-\frac{1}{2}\right)-\left(\frac{1}{5}x-\frac{2}{3}\right)\left(4\frac{x^2}{3}+1\right)=\frac{22}{45}x^2\)
\(\Leftrightarrow36x^2\left(\frac{x}{3}-\frac{1}{2}\right)-45\left(\frac{x}{5}-\frac{2}{3}\right)\left(\frac{4x^2}{3}+1\right)=22x^2\)
\(\Leftrightarrow12x^3-18x^2-12x^3-9x+40x^2+30=22x^2\)
\(\Leftrightarrow22x^2-9x+30=22x^2\)
\(\Leftrightarrow-9x+30=0\)
\(\Leftrightarrow-9x=-30\)
\(\Leftrightarrow x=\frac{10}{3}\)
Tìm x biết :
a) 3(5/3x-7)-2(1.5x+6)-(5-x)(x+4)=80+x^2
b) 4/5x^2(x/3-1/2)-(1/5x-2/3)(4x^2/3+1)=22/45x^2
1/ Ta có: \(5x\left(x-3\right)=\left(x-2\right)\left(5x-1\right)-5\)
\(\Rightarrow5x^2-15x=5x^2-11x+2-5\)
\(\Rightarrow-15x=-11x-3\)
\(\Rightarrow-15x+11x=-3\)
\(\Rightarrow-4x=-3\Rightarrow x=\frac{3}{4}\).
2/ Ta có: \(\left(2x-1\right)\left(x-2\right)-\left(x+3\right)\left(2x-7\right)=3\)
\(\Rightarrow2x^2-5x+2-2x^2+x+21-3=0\)
\(\Rightarrow-4x+20=0\Rightarrow-4x=-20\Rightarrow x=5\).
Chúc bn hc tốt!
1/ \(5x\left(x-3\right)=\left(x-2\right)\left(5x-1\right)-5\)
<=> \(5x^2-15x=\left(5x^2-x-10x+2\right)-5\)
<=> \(5x^2-15x=5x^2-11x-3\)
<=> \(5x^2-15x-5x^2+11x+3=0\)
<=> \(-4x+3=0\)
<=> \(x=\frac{3}{4}\)
2/ \(\left(2x-1\right)\left(x-2\right)-\left(x+3\right)\left(2x-7\right)=3\)
<=> \(2x^2-4x-x+2-\left(2x^2-7x+6x-21\right)=3\)
<=> \(2x^2-5x+2-2x^2+x+21=3\)
<=> \(-4x+21=3\)
<=> \(4x=17\)
<=> \(x=\frac{17}{4}\)
a: =>2^4x<2^28
=>4x<28
=>x<7
b: =>5^3x+3<5
=>3x+3<1
=>3x<-2
=>x<-2/3
x=2
100%
2x+2.3x+1.5x=10800
2x.22.3x.2.5x=10800
(2.3.5)x.12=10800
30x=10800:12
30x=900
\(30^{^{ }m}\)\(30^2\Rightarrow x=2\)