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a: =>x^3-3x^2+3x^2-9x+4x-12+a+12 chia hết cho x-3
=>a+12=0
=>a=-12
b: =>2x^2-6x+5x-15+a+15 chia hết cho x-3
=>a+15=0
=>a=-15
c: =>x^3-2x^2-5x^2+20+a-20 chia hết cho x-2
=>a-20=0
=>a=20
e: =>10x^2-15x+8x-12+a+12 chia hết cho 2x-3
=>a+12=0
=>a=-12
f: =>5x^3-x^2+5x^2-x-5x+1-a-1 chia hết cho 5x-1
=>-a-1=0
=>a=-1
khồng dám đâu mị còn pải học pài sao khó ghê mị còn pải học bài
\(\frac{2x+3}{6}=\frac{7x-3}{15}\)
⇔ 15( 2x + 3 ) = 6( 7x - 3 )
⇔ 30x + 45 = 42x - 18
⇔ 30x - 42x = -18 - 45
⇔ -12x = -63
⇔ x = 21/4
\(\frac{2x+3}{6}=\frac{7x-3}{15}\)
\(15\left(2x+3\right)=6\left(7x-3\right)\)
\(30x+45=42x-18\)
\(30x-42x=-18-45\)
\(-12x=-63\)
\(x=\frac{21}{4}\)
\(\frac{2x+3}{6}=\frac{7x-3}{15}\)
\(\Rightarrow\frac{5.\left(2x+3\right)}{30}=\frac{2.\left(7x-3\right)}{30}\)
\(\Rightarrow5.\left(2x+3\right)=2.\left(7x-3\right)\)
\(\Rightarrow10x+15=14x-6\)
\(\Rightarrow10x-14x=-6-15\)
\(\Rightarrow-4x=-21\)
\(\Rightarrow x=-21:\left(-4\right)\)
\(\Rightarrow x=\frac{21}{4}\)
\(2x+\frac{3}{6}=7x-\frac{3}{15}\)
\(2x+\frac{1}{2}=7x-\frac{1}{5}\)
\(2x-7x=-\frac{1}{5}-\frac{1}{2}\)
\(-5x=-\frac{7}{10}\)
\(x=\frac{7}{50}\)
c , d giải nốt:
c) 2x + 3/6 = 7x - 13/15
=> (2x + 3) . 15 = (7x - 13) x 6
=> 30x +45 = 42x - 78
=> 30x - 42x = -78 - 45
=> -12x = -123
=> x = 41/4
d) 2-x/4 = 3x - 1/ - 3
=> (2-x) . -3 = 4. (3x - 1)
=> -6 - (-3x) = 12x - 4
(-6) + 4 = 12x - - (-3x)
=> -2 = 9x
=> x = -2/9
\(1,\frac{x+1}{x-2}=\frac{3}{4}\)
\(\Rightarrow3x-6=4x+4\)
\(\Rightarrow3x-4x=4+6\)
\(\Rightarrow-x=10\Leftrightarrow x=-10\)
\(2,\frac{x-1}{3}=\frac{x+3}{5}\)
\(\Rightarrow5x-5=3x+9\)
\(\Rightarrow5x-3x=9+5\)
\(\Rightarrow2x=14\Leftrightarrow x=7\)
\(3,\frac{2x+3}{24}=\frac{3x-1}{32}\)
\(\Rightarrow64x+96=72x-24\)
\(\Rightarrow72x-64x=24+96\)
\(\Rightarrow8x=120\)
\(\Rightarrow x=15\)
/5x-4/=/x+2/
\(\orbr{\begin{cases}5x-4=x+2\\5x-4=-x+2\end{cases}}suyra\orbr{\begin{cases}x=\frac{3}{2}\\x=\frac{1}{2}\end{cases}}\)
vậy x=3/2 hoặc x=1/2
\(\left|2x-\frac{1}{2}\right|+1=3x\)
\(\Leftrightarrow\left|2x-\frac{1}{2}\right|=3x-1\)
\(\Leftrightarrow\orbr{\begin{cases}2x-\frac{1}{2}=3x-1\\2x-\frac{1}{2}=1-3x\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}2x-3x=-1+\frac{1}{2}\\2x+3x=1+\frac{1}{2}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}-x=-\frac{1}{2}\\5x=\frac{3}{2}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=\frac{3}{10}\end{cases}}\)
\(3x+\frac{3}{6}=7x+\frac{3}{15}\)
\(\Rightarrow4x=\frac{3}{10}\Rightarrow x=\frac{3}{40}\)
Ta co:
2x+3/6 = 7x + 3/15
=> 3/6 = 5x + 3/15
=> x = (3/6 - 3/15):5 = 3/50