Toán Tìm x biết a (x-8).(x mũ 3+8)=0 b (4x-3)-(x+5)=3.(10-x) 02/08/2021 By Melody Tìm x biết a (x-8).(x mũ 3+8)=0 b (4x-3)-(x+5)=3.(10-x)
`a.(x-8)(x+8)=0` `⇔$\left \{ {{x-8=0} \atop {x³+8=2}} \right.$ ` `⇔$\left \{ {{x=8} \atop {x³=-2³}} \right.$ ` `⇔$\left \{ {{x=8} \atop {x=-2}} \right.$` Vậy ` x = 8;-2` `b. ( 4 x − 3 ) − ( x + 5 ) = 3 . ( 10 − x )` `⇔ 4 x − 3 − x − 5 = 30 − 3 x` `⇔ 3 x − 8 = 30 − 3 x` `⇔ 3 x + 3 x = 30 + 8` `⇔ 6 x = 38` `⇔ x = 19/ 3` Vậy ` x = 19/ 3` Xin hay nhất Trả lời
Đáp án: `a, x=-2,x=8` `b, x=(19)/3` Giải thích các bước giải: `a,(x-8)(x³+8)=0` `<=>`\(\left[ \begin{array}{l}x-8=0\\x³+8=0\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x=8\\x³=-8\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x=8\\x³=(-2)^³\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=8\\x=-2\end{array} \right.\) Vậy `x=-2, x=8` _________________ `b, (4x-3)-(x+5)=3.(10-x)` `<=> 4x -3 -x -5 =30-3x` `<=> 3x -8 =30-3x` `<=> 3x +3x =30+8` `<=> 6x =38` `<=> x= (19)/3` Vậy `x=(19)/3` Trả lời
`a.(x-8)(x+8)=0`
`⇔$\left \{ {{x-8=0} \atop {x³+8=2}} \right.$ `
`⇔$\left \{ {{x=8} \atop {x³=-2³}} \right.$ `
`⇔$\left \{ {{x=8} \atop {x=-2}} \right.$`
Vậy ` x = 8;-2`
`b. ( 4 x − 3 ) − ( x + 5 ) = 3 . ( 10 − x )`
`⇔ 4 x − 3 − x − 5 = 30 − 3 x`
`⇔ 3 x − 8 = 30 − 3 x`
`⇔ 3 x + 3 x = 30 + 8`
`⇔ 6 x = 38`
`⇔ x = 19/ 3`
Vậy ` x = 19/ 3`
Xin hay nhất
Đáp án:
`a, x=-2,x=8`
`b, x=(19)/3`
Giải thích các bước giải:
`a,(x-8)(x³+8)=0`
`<=>`\(\left[ \begin{array}{l}x-8=0\\x³+8=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=8\\x³=-8\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=8\\x³=(-2)^³\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=8\\x=-2\end{array} \right.\)
Vậy `x=-2, x=8`
_________________
`b, (4x-3)-(x+5)=3.(10-x)`
`<=> 4x -3 -x -5 =30-3x`
`<=> 3x -8 =30-3x`
`<=> 3x +3x =30+8`
`<=> 6x =38`
`<=> x= (19)/3`
Vậy `x=(19)/3`