Tính
7.9-14 / 3-17
25%-3/2+0,5.12/5.25%-1
Tìm x
( 14/5x + 50 ) :2/3 = -51
8x-0,4 = 7,8x + 402
Giúp mik hết nha r Mik sẽ vote + CTLHN
Tính 7.9-14 / 3-17 25%-3/2+0,5.12/5.25%-1 Tìm x ( 14/5x + 50 ) :2/3 = -51 8x-0,4 = 7,8x + 402 Giúp mik hết nha r Mik sẽ vote + CTLHN
By Madeline
7.9- 14/3- 17
=7.9-(7.2)tất cả trên 3-17
=7.(9-2) tất cả trên 3-17
=7.7 tất cả trên 3-17
=-49/51
25%- 3/2 + 0,5. 12/5. 25%- 1
=1/4 – 3/2 + 1/2.12/5. 1/4- 1
=1/4 – 3/2 + 6/5.1/4-1
=1/4 – 3/2 + 3/10-1
=5/20 – 30/20 + 6/20 – 20/20
= -25/20 -14/20
= -39/20
(14/5x + 50): 2/3= -51
14/5x + 50= -51. 2/3
14/5x + 50= -102/3
14/5x= -102/3-50
14/5x= -102/3- 150/3
14/5x= -252/3
x= -252/3: 14/5
x= -252/3. 5/14
x= -30 Vậy x=-30
8x-04= 7,8 +402
8x-2/5= 39/5 +402
8x-39/5= 2/5+ 402
x.(8-39/5)= 2/5+ 2010/5
x.(40/5-39/5)= 2012/5
x.1/5= 2012/5
x= 2012/5:1/5
x= 2012/5. 5
x= 2012
Nhớ vote mình 5???? nhé!
Đáp án:
Giải thích các bước giải:
7.9-14 / 3-17
$=\frac{7. 9- 7.2}{-14}$
$= \frac{7. (9- 2)}{-14}$
$= \frac{7. 7}{-14}$
$= \frac{49}{-14}$
$= \frac{-7}{2}$ (đổi dấu)
`25\%-3/2+0,5.12/5.2\5%-1`
$= \frac{1}{4}- \frac{3}{2}+ \frac{1}{2}. \frac{12}{5}. \frac{1}{4}- 1$
$= \frac{1}{4}- \frac{3}{2}+ \frac{3}{10}- 1$
$= \frac{5}{20}- \frac{30}{20}+ \frac{6}{20}$
$= \frac{5- 30+ 6}{20}= \frac{-21}{20}$
Tìm `x`
`( 14/5x + 50 ) :2/3 = -51`
$\frac{14}{5}x+ 50= -51. \frac{2}{3}$
$\frac{14}{5}x+ 50= -34$
$\frac{14}{5}x = -34- 50$
$\frac{14}{5}x= -84$
$x= -84: \frac{14}{5}$
$x= -30$
`8x-0,4 = 7,8x + 402`
$8x- 7,8. x= 402+ 0,4$
$0, 2. x= 402,04$
$x= 402,04: 2$
$x= 2012$