Toán a,2x^3+6x^2=x^2+3x b,(3x-1)(x^2+2)=(3x-1)(7x-10) 18/10/2021 By aikhanh a,2x^3+6x^2=x^2+3x b,(3x-1)(x^2+2)=(3x-1)(7x-10)
` 2x^3 + 6x^2 = x^2+3x` ` => 2x^3 + 6x^2 -x^2-3x = 0` ` => 2x^3 +5x^2 -3x = 0` ` => x(2x^2 +5x -3) = 0` ` => x(2x^2 + 6x – x -3) = 0` ` => x(2x-1)(x+3) = 0` ` => x= 0` hoặc ` 2x -1 = 0` hoặc ` x +3 =0` `=> x= 0` hoặc ` x = 1/2` hoặc ` x=-3` Vậy ` x \in { -3 ; 0 ; 1/2}` `b)` ` (3x-1)(x^2+2) = (3x-1)(7x-10)` Với ` 3x -1 = 0 <=> x= 1/3` khi đó ` 0 *(x^2+2) = 0 * (7x-10)` ` => 0 = 0` ( đúng ) Vậy ` x= 1/3` thỏa mãn Với ` x \ne 1/3` ` (3x-1)(x^2+2) = (3x-1)(7x-10)` ` => x^2 +2 = 7x -10` ` => x^2 -7x +12 = 0` ` => (x-3)(x-4) =0` ` =>` \(\left[ \begin{array}{l}x-3=0\\x-4-=0\end{array} \right.\) `=>` \(\left[ \begin{array}{l}x=3\\x=4\end{array} \right.\) Vậy ` x \in{3;4}` Trả lời
a,2x³+6x²=x²+3x <=> 2x³ + 6x² – x² – 3x = 0 <=> 2x³ – 5x² – 3x = 0 <=> \(\left[ \begin{array}{l}x=-0,5\\x=0,3\end{array} \right.\) b,(3x-1)(x²+2)=(3x-1)(7x-10) <=>x² + 2 = 7x – 10 <=> x² – 7x + 12 = 0 <=> \(\left[ \begin{array}{l}x=3\\x=4\end{array} \right.\) Trả lời
` 2x^3 + 6x^2 = x^2+3x`
` => 2x^3 + 6x^2 -x^2-3x = 0`
` => 2x^3 +5x^2 -3x = 0`
` => x(2x^2 +5x -3) = 0`
` => x(2x^2 + 6x – x -3) = 0`
` => x(2x-1)(x+3) = 0`
` => x= 0` hoặc ` 2x -1 = 0` hoặc ` x +3 =0`
`=> x= 0` hoặc ` x = 1/2` hoặc ` x=-3`
Vậy ` x \in { -3 ; 0 ; 1/2}`
`b)`
` (3x-1)(x^2+2) = (3x-1)(7x-10)`
Với ` 3x -1 = 0 <=> x= 1/3` khi đó
` 0 *(x^2+2) = 0 * (7x-10)`
` => 0 = 0` ( đúng )
Vậy ` x= 1/3` thỏa mãn
Với ` x \ne 1/3`
` (3x-1)(x^2+2) = (3x-1)(7x-10)`
` => x^2 +2 = 7x -10`
` => x^2 -7x +12 = 0`
` => (x-3)(x-4) =0`
` =>` \(\left[ \begin{array}{l}x-3=0\\x-4-=0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=3\\x=4\end{array} \right.\)
Vậy ` x \in{3;4}`
a,2x³+6x²=x²+3x
<=> 2x³ + 6x² – x² – 3x = 0
<=> 2x³ – 5x² – 3x = 0
<=> \(\left[ \begin{array}{l}x=-0,5\\x=0,3\end{array} \right.\)
b,(3x-1)(x²+2)=(3x-1)(7x-10)
<=>x² + 2 = 7x – 10
<=> x² – 7x + 12 = 0
<=> \(\left[ \begin{array}{l}x=3\\x=4\end{array} \right.\)