a) (x-2)(x+10)/3-(x+4)(x+10)/12=(x-2)(x+4)/4
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Tìm xx biết: \left(x^{4}\right)^{3}=\dfrac{x^{19}}{x^{6}}(x4)3=x6x19
Trả lời: x=x=
\(\Leftrightarrow4\left(x-2\right)\left(x+10\right)-\left(x+4\right)\left(x+10\right)-3\left(x-2\right)\left(x+4\right)=0\)
\(\Leftrightarrow4\left(x^2+8x-20\right)-\left(x^2+14x+40\right)-3\left(x^2+2x-8\right)=0\)
\(\Leftrightarrow12x-96=0\Rightarrow x=8\)
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
Trả lời:
7, 5( x + y )2 + 15( x + y )
= 5( x + y )( x + y + 3 )
9, 7x( y - 4 )2 - ( 4 - y )3
= 7x ( 4 - y )2 - ( 4 - y )
= ( 4 - y )2 ( 7x - 4 + y )
11, ( x + 1 )( y - 2 ) - ( 2 - y )2
= ( x + 1 )( y - 2 ) - ( y - 2 )2
= ( y - 2 )( x + 1 - y + 2 )
= ( y - 2 )( x - y + 3 )
8, 9x ( x - y ) - 10 ( y - x )2
= 9x ( x - y ) - 10 ( x - y )2
= ( x - y )[ ( 9x - 10 ( x - y ) ]
= ( x - y )( 9x - 10x + 10y )
= ( x - y )( 10y - x )
10, ( a - b )2 - ( a + b )( b - a )
= ( b - a )2 - ( a + b )( b - a )
= ( b - a )( b - a - a - b )
= - 2a( b - a )
= 2a ( a - b )
12, 2x ( x - 3 ) + y ( x - 3 ) + ( 3 - x )
= 2x ( x - 3 ) + y ( x - 3 ) - ( x - 3 )
= ( x - 3 )( 2x + y - 1 )
a) \(3x-10=2x+13\)
\(\Leftrightarrow3x-2x=13+10\)
\(\Leftrightarrow x=23\)
b) \(x+12=-5-x\)
\(\Leftrightarrow x+x=-5-12\)
\(\Leftrightarrow2x=-17\)
\(\Leftrightarrow x=-\frac{17}{2}\)
c) \(x+5=10-x\)
\(\Leftrightarrow x+x=10-5\)
\(\Leftrightarrow2x=5\)
\(\Leftrightarrow x=\frac{5}{2}\)
d) \(6x+2^3=2x-12\)
\(\Leftrightarrow6x+8=2x-12\)
\(\Leftrightarrow6x-2x=-12-8\)
\(\Leftrightarrow4x=-20\)
\(\Leftrightarrow x=-5\)
e) \(12-x=x+1\)
\(\Leftrightarrow-x-x=1-12\)
\(\Leftrightarrow-2x=-11\)
\(\Leftrightarrow x=\frac{11}{2}\)
g) \(2\left(x-1\right)+3\left(x-2\right)=x-4\)
\(\Leftrightarrow2x-2+3x-6=x-4\)
\(\Leftrightarrow2x+3x-x=-4+6+2\)
\(\Leftrightarrow4x=4\)
\(\Leftrightarrow x=1\)
h) \(14+4x=3x+20\)
\(\Leftrightarrow4x-3x=20-14\)
\(\Leftrightarrow x=6\)
i) \(4\left(2x+7\right)-3\left(3x-2\right)=24\)
\(\Leftrightarrow8x+28-9x+6=24\)
\(\Leftrightarrow8x-9x=24-6-28\)
\(\Leftrightarrow-x=-10\)
\(\Leftrightarrow x=10\)
k) \(3\left(4-x\right)-2\left(x-1\right)=x+20\)
\(\Leftrightarrow12-3x-2x+2=x+20\)
\(\Leftrightarrow-3x-2x-x=20-2-12\)
\(\Leftrightarrow-6x=6\)
\(x=-1\)
l) \(3\left(x-2\right)+2x=10\)
\(\Leftrightarrow3x-6+2x=10\)
\(\Leftrightarrow3x+2x=10+6\)
\(\Leftrightarrow5x=16\)
\(\Leftrightarrow x=\frac{16}{5}\)
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((x - 2)(x + 10))/3 - ((x + 40)(x + 10))/12 = ((x - 2)(x + 4))/4
<=> 4(x - 2)(x + 10) - (x + 4)(x + 10) = 3(x - 2)(x + 4)
<=> 4x^2 + 40x - 8x - 80 - x^2 - 10x - 4x - 40 = 3x^2 + 12x - 6x - 24
<=> 3x^2 + 18x - 120 = 3x^2 + 6x - 24
<=> 18x - 120 = 6x - 24
<=> 18x - 120 - 6x = -24
<=> 12x - 120 = -24
<=> 12x = -24 + 120
<=> 12x = 96
<=> x = 8