Giải hộ mình với ạ
a) 2(x-3)=-3(x-1)+7
b) (x^2-1)(x-2)(x-3)=0
c) |5x-3|=x+7
Giải hộ mình với ạ a) 2(x-3)=-3(x-1)+7 b) (x^2-1)(x-2)(x-3)=0 c) |5x-3|=x+7
By Samantha
By Samantha
Giải hộ mình với ạ
a) 2(x-3)=-3(x-1)+7
b) (x^2-1)(x-2)(x-3)=0
c) |5x-3|=x+7
Bạn tham khảo nha!
`a)` `2(x – 3) = -3(x -1) + 7`
`⇔` `2x – 6 = -3x + 3 + 7`
`⇔` `2x – 6 = -3x + 10`
`⇔` `2x – 6 + 3x – 10 = 0`
`⇔` `5x – 16 = 0`
`⇔` `5x = 16`
`⇔` `x = \frac{16}{5}`
`S = {\frac{16}{5}}`
`b)` `(x^2 -1)(x – 2)(x – 3) = 0`
`⇔` `(x – 1)(x + 1)(x – 2)(x – 3) = 0`
`⇔` \(\left[ \begin{array}{l}x – 1 = 0\\x + 1 = 0\\x – 2 = 0\\x – 3 = 0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x = 1\\x = -1\\x = 2\\x = 3\end{array} \right.\)
`S = {-1; 1; 2; 3}`
`c)` `|5x – 3| = x + 7`; ĐKXĐ: `x \ge – 7`
`->` \(\left[ \begin{array}{l}5x – 3 = x +7\\5x – 3 =-(x + 7)\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}5x – 3 – x – 7 = 0\\5x + x = – 7 + 3\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}4x – 10 = 0\\6x = -4\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}4x = 10 \\x = \dfrac{-2}{3}\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x = \dfrac{5}{2}\\x= \dfrac{-2}{3}\end{array} \right.\)
`S = {\frac{5}{2}; \frac{-2}{3}}`
Đáp án:+Giải thích các bước giải:
`a)2(x-3)=-3(x-1)+7`
`<=>2x-6=-3x+3+7`
`<=>2x+3x=3+7+6`
`<=>5x=16`
`<=>x=16/5`
`Vậy` `x=16/5`
`b)(x^2-1)(x-2)(x-3)=0`
`<=>`\(\left[ \begin{array}{l}x^2-1=0\\x-2=0\\x-3=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x^2=1\\x=2\\x=3\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=±1\\x=2\\x=3\end{array} \right.\)
`Vậy` `x∈{-1;1;2;3}`
`c)|5x-3|=x+7(x ge -7)`
`<=>5x-3=x+7` hoặc `5x-3=-(x+7)`
`<=>4x=10` hoặc `5x+x=-7+3`
`<=>x=5/2(tm)` hoặc `x=-2/3(tm)`
`Vậy` `S={5/2;-2/3}`