a, x+5=10-x
b.x+12=-5-x
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`-|2x-3|=4-x`
`<=>|2x-3|=x-4(x>=4)`
`+)2x-3=x-4`
`<=>x=-1(l)`
`+)2x-3=4-x`
`<=>3x=7`
`<=>x=7/3(l)`
Vậy PT vô nghiệm.
`x^2=9(x-1)^2`
`<=>x^2=[3(x-1)]^2`
`<=>x^2=(3x-3)^2`
`<=>(2x-3)(4x-3)=0`
`<=>` \(\left[ \begin{array}{l}x=\dfrac23\\x=\dfrac43\end{array} \right.\)
Vậy `S={2/3,4/3}`.
Bài 2:
a: \(\Leftrightarrow12x-8x^2+8x^2-12x-8+12x=4\)
\(\Leftrightarrow12x=12\)
hay x=1
b: \(\Leftrightarrow\left(x-4\right)\left(x-3\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=3\\x=-3\end{matrix}\right.\)
a, \(\dfrac{5\times11\times15\times18}{6\times15\times22\times10}\)
= \(\dfrac{5\times11\times15\times6\times3}{6\times15\times11\times2\times2\times5}\)
= \(\dfrac{5\times11\times15\times6}{5\times11\times15\times6}\) \(\times\) \(\dfrac{3}{2\times2}\)
= 1 \(\times\) \(\dfrac{3}{4}\)
= \(\dfrac{3}{4}\)
b, \(\dfrac{7}{12}\) \(\times\) \(\dfrac{3}{5}\) + \(\dfrac{3}{5}\) \(\times\) \(\dfrac{5}{12}\)
= \(\dfrac{3}{5}\) \(\times\) ( \(\dfrac{7}{12}+\dfrac{5}{12}\))
= \(\dfrac{3}{5}\) \(\times\) \(\dfrac{12}{12}\)
= \(\dfrac{3}{5}\) \(\times\) 1
= \(\dfrac{3}{5}\)
a) 1 . 5 . 6 + 2 . 10 . 12 = A
1 . 5 . 6 + 1 . 2 . 5 . 2 . 6 . 2 = A
1 . 5 . 6 . ( 1 + 2. 2 . 2 ) = A
30 . 9 = A
270 = A
b) 1 . 3 . 5 + 2 . 6 . 10 = B
1 . 3 . 5 + 1 . 2 . 3 . 2 . 5 . 2 = B
1 . 3 . 5 . ( 1 + 2 . 2 . 2 ) = B
15 . 9 = B
135 = B
c) A : B = A/B
x+x=-5-12
x+x=-17
x.(1+1)=-17
x.2=-17
x=-17:2
x=-8,5
vậy x=-8,5
x+x=10-5
x+x=5
x.(1+1)=5
x.2=5
x=5:2
x=2,5
vậy x=2,5
Hướng dẫn giải:
a) 5 x (10 + 9)
Cách 1:
5 x (10 + 9) = 5 x 19 = 95
Cách 2:
5 x (10 + 9) = 5 x 10 + 5 x 9 = 50 + 45 = 95
b) 10 x (30 + 5)
Cách 1:
10 x (30 + 5) = 10 x 35 = 350
Cách 2:
10 x (30 + 5) = 10 x 30 + 10 x 5 = 300 + 50 = 350
Hướng dẫn giải nè :
a) 5 x (10 + 9)
Cách 1:
5 x (10 + 9) = 5 x 19 = 95
Cách 2:
5 x (10 + 9) = 5 x 10 + 5 x 9 = 50 + 45 = 95
b) 10 x (30 + 5)
Cách 1:
10 x (30 + 5) = 10 x 35 = 350
Cách 2:
10 x (30 + 5) = 10 x 30 + 10 x 5 = 300 + 50 = 350
a) x+5=10-x
<=> x+x=10-5
<=> 2x=5
<=> x=\(\frac{5}{2}\)
b) \(x+12=-5-x\)
\(\Leftrightarrow x+x=-5-12\)
\(\Leftrightarrow2x=-17\)
\(\Leftrightarrow x=\frac{-17}{2}\)
a, x+5=10-x
<=> x+x=10-5
<=> 2x=5
<=>x=5/2
Vậy x=5/2
b, x+12=-5-x
<=> x+x=-5-12
<=> 2x=-17
<=>x=-17/2
Vậy x=-17/2