giúp mik bài này vs:
Tìm x, biết:
a, x – 25% . x = 1/2
b, ( 50% . x + 9/4) . -2/3 = 17/6
c, ( 4/3 – 25% – 5/12) – 2 . x = 1,6 : 3/5
giúp mik bài này vs:
Tìm x, biết:
a, x – 25% . x = 1/2
b, ( 50% . x + 9/4) . -2/3 = 17/6
c, ( 4/3 – 25% – 5/12) – 2 . x = 1,6 : 3/5
`x – 25% . x = 1/2`
`=> x – 1/4 . x = 1/2`
`=> x . (1 – 1/4) = 1/2`
`=> x . 3/4 = 1/2`
`=> x = 2/3`
—
`(50% . x + 9/4) . (-2)/3 = 17/6`
`=> 1/2 . x + 9/4 = 17/6 : (-2)/3`
`=> 1/2 . x + 9/4 = (-17)/4`
`=> 1/2 . x = (-17)/4 – 9/4`
`=> 1/2 . x = (-13)/2`
`=> x = (-13)/2 : 1/2`
`=> x = -13`
—
`(4/3 – 25% – 5/12) – 2 . x = 1,6 : 3/5`
`=> (4/3 – 1/4 – 5/12) – 2x = 8/3`
`=> (16/12 – 3/12 – 5/12) – 2x = 8/3`
`=> 2/3 – 2x = 8/3`
`=> 2x = 2/3 – 8/3`
`=> 2x = -2`
`=> x = -1`
Đáp án:
$a)$$x=\frac{2}{3}$
$b)$$x=-13$
$c)$$x=\frac{-1}{3}$
Giải thích các bước giải:
$a)x-25$%$.x=\frac{1}{2}$
$x-\frac{1}{4}.x=$ $\frac{1}{2}$
$x.(1-\frac{1}{4})=$ $\frac{1}{2}$
$x.\frac{3}{4}=$ $\frac{1}{2}$
$x=\frac{1}{2}:$ $\frac{3}{4}$
$x=\frac{1}{2}×\frac{4}{3}$
$x=\frac{4}{6}=\frac{2}{3}$
$b)(50$%$.x+\frac{9}{4}).$ $\frac{-2}{3}=$ $\frac{17}{6}$
$(50$%$.x+\frac{9}{4})=$$\frac{17}{6}:$ $\frac{-2}{3}$
$(50$%$.x+\frac{9}{4})=$$\frac{17}{6}×$ $\frac{3}{-2}$
$(50$%$.x+\frac{9}{4})=$$\frac{51}{-12}=\frac{-17}{4}$
$50$%$.x=$$\frac{-17}{4}-\frac{9}{4}$
$50$%$.x=$$\frac{-13}{2}$
$\frac{1}{2}.x=$$\frac{-13}{2}$
$x=\frac{-13}{2}:\frac{1}{2}$
$x=-13$
$c) (\frac{4}{3}-25$%$-$ $\frac{5}{12})-2.x=1,6:$ $\frac{3}{5}$
$(\frac{4}{3}-25$%$-$$\frac{5}{12})-2.x=$$\frac{8}{5}:$ $\frac{3}{5}$
$(\frac{4}{3}-25$%$-$$\frac{5}{12})-2.x=$ $\frac{8}{3}$
$(\frac{4}{3}-\frac{1}{4}-\frac{5}{12})-2.x=$ $\frac{8}{3}$
$\frac{16-3-5}{12}-2.x=$ $\frac{8}{3}$
$\frac{8}{12}-2.x=\frac{8}{3}$
$\frac{2}{3}-2.x=\frac{8}{3}$
$2.x=\frac{2}{3}-\frac{8}{3}$
$2.x=-2$
$x=-2:2$
$x=-1$