$1)1,4.\frac{15}{49}-($ $\frac{4}{5}+$ $\frac{2}{3}):2$ $\frac{1}{5}$
$2)(\frac{-2}{3}+1$ $\frac{1}{4}-$ $\frac{1}{6}).$ $\frac{-24}{10}:0,5$
$3)1\frac{2}{3}+[0,25:(10,3-9,8)-$ $\frac{3}{4}]$
$4)(\frac{5}{7}.0,6-5:3$ $\frac{1}{2}).(40phần trăm-1,4).(-2)³$
$5)B=\frac{13}{15}.0,25.3+($ $\frac{8}{15}-1$ $\frac{19}{60}):1$ $\frac{23}{24}$
$6)\frac{1}{2}x+$ $\frac{3}{5}(x-2)=3$
$7)\frac{1}{3}x-0,5x=0,75$
$8)(2,4x-36):1\frac{5}{7}=-1$
$9)(\frac{3}{4}x+2$ $\frac{1}{2}).$ $\frac{-2}{3}=$ $\frac{1}{8}$
$10)(3\frac{1}{2}+2x)2$ $\frac{2}{3}=5$ $\frac{1}{3}$
$11)3\frac{1}{3}x+16$ $\frac{3}{4}=-13,25$
Đáp án:
Giải thích các bước giải:
`1) 1,4 . 15/49 – (4/5 + 2/3) : 2 1/5`
`= 7/5 . 15/49 – (12/15 + 10/15) : 11/5`
`= 3/7 – 22/15 . 5/11`
`= 3/7 – 2/3`
`= 9/21 – 14/21 = (-5)/21`
.
`2) ((-2)/3 + 1 1/4 – 1/6). (-24)/10 : 0,5`
`= ((-2)/3 + 5/4 – 1/6) . (-12)/5 . 2`
`= ((-8)/12 + 15/12 – 2/12) . (-24)/5`
`= 5/12 . (-24)/5 = -2`
.
`3) 1 2/3 + [0,25 : (10,3 – 9,8) – 3/4]`
`= 5/3 + [0,25 : 0,5 – 3/4]`
`= 5/3 + [0,5 – 3/4]`
`= 5/3 + 1/2 – 3/4`
`= 20/12 + 6/12 – 9/12`
`= 17/12`
.
`4) (5/7 . 0,6 – 5 : 3 1/2) . (40% – 1,4) . (-2)^3`
`= (5/7 . 3/5 – 5 : 7/2) . (0,4 – 1,4) . (-8)`
`= (3/7 – 5 . 7/2) . (-1) . (-8)`
`= (3/7 – 10/7) . 8`
`= (-1) . 8 = -8`
.
`5) B = 13/15 . 0,25 . 3 + (8/15 – 1 19/60) : 1 23/24`
`= 13/15 . 1/4 . 3 + (8/15 – 79/60) : 47/24`
`= 13/20 + (32/60 – 79/60) . 24/47`
`= 13/20 + (-47)/60 . 24/47`
`= 13/20 + (-2)/5`
`= 13/20 – 8/20 = 1/4`
.
`6) 1/2 x + 3/5 (x – 2) = 3`
`⇒ 1/2 x + 3/5 x – 6/5 = 3`
`⇒ (1/2 + 3/5)x = 3 + 6/5`
`⇒ (5/10 + 6/10) x = 15/5 + 6/5`
`⇒ 11/10 x = 21/5`
`⇒ x = 21/5 : 11/10`
`⇒ x = 21/5 . 10/11`
`⇒ x = 42/11`
.
`7) 1/3 x – 0,5 x = 0,75`
`⇒ 1/3 x – 1/2 x = 3/4`
`⇒ (1/3 – 1/2)x = 3/4`
`⇒ (2/6 – 3/6)x = 3/4`
`⇒ (-1)/6 x = 3/4`
`⇒ x = 3/4 : (-1)/6`
`⇒ x = 3/4 . (-6)`
`⇒ x = (-9)/2`
.
`8) (2,4 x – 36) : 1 5/7 = -1`
`⇒ 12/5 x – 36 = (-1) . 1 5/7`
`⇒ 12/5 x – 36 = (-1) . 12/7`
`⇒ 12/5 x – 36 = (-12)/7`
`⇒ 12/5 x = (-12)/7 + 36`
`⇒ 12/5 x = (-12)/7 + 252/7`
`⇒ 12/5 x = 240/7`
`⇒ x = 240/7 : 12/5`
`⇒ x = 240/7 . 5/12`
`⇒ x = 100/7`
.
`9) (3/4 x + 2 1/2) . (-2)/3 = 1/8`
`⇒ 3/4 x + 5/2 = 1/8 : (-2)/3`
`⇒ 3/4 x + 5/2 = 1/8 . (-3)/2`
`⇒ 3/4 x + 5/2 = (-3)/16`
`⇒ 3/4 x = (-3)/16 – 5/2`
`⇒ 3/4 x = (-3)/16 – 40/16`
`⇒ 3/4 x = (-43)/16`
`⇒ x = (-43)/16 : 3/4`
`⇒ x = (-43)/16 . 4/3`
`⇒ x = (-43)/12`
.
`10) (3 1/2 + 2x) . 2 2/3 = 5 1/3`
`⇒ (7/2 + 2x) . 8/3 = 16/3`
`⇒ 7/2 + 2x = 16/3 : 8/3`
`⇒ 7/2 + 2x = 16/3 . 3/8`
`⇒ 7/2 + 2x = 2`
`⇒ 2x = 2 – 7/2`
`⇒ 2x = 4/2 – 7/2`
`⇒ 2x = (-3)/2`
`⇒ x = (-3)/2 : 2`
`⇒ x = (-3)/2 . 1/2`
`⇒ x = (-3)/4`
.
`11) 3 1/3 x + 16 3/4 = -13,25`
`⇒ 10/3 x + 16,75 = -13,25`
`⇒ 10/3 x = -13,25 – 16,75`
`⇒ 10/3 x = -30`
`⇒ x = -30 : 10/3`
`⇒ x = -30 . 3/10`
`⇒ x = -9`