1,tính.
a,38×67+33×38
b, 49+785+51
c, 87×134-34×87
d, 5/4×1/3+2/3×5/4
e, 7/2×5/3-2/3×7/2
f, 4×89×25
1,tính. a,38×67+33×38 b, 49+785+51 c, 87×134-34×87 d, 5/4×1/3+2/3×5/4 e, 7/2×5/3-2/3×7/2 f, 4×89×25
By Caroline
By Caroline
1,tính.
a,38×67+33×38
b, 49+785+51
c, 87×134-34×87
d, 5/4×1/3+2/3×5/4
e, 7/2×5/3-2/3×7/2
f, 4×89×25
Đáp án:
Bài 1: tính
a) 38 x 67 + 33 x 38
= 38 x (67 + 33)
= 38 x 100
= 3800
b) 49 + 785 + 51
= (49 + 51) + 785
= 100 + 785
= 885
c) 87 x 134 – 34 x 87
= 87 x (134 – 34)
= 87 x 100
= 8700
d) $\dfrac{5}{4}$ x $\dfrac{1}{3}$ + $\dfrac{2}{3}$ x $\dfrac{5}{4}$
= $\dfrac{5}{4}$ x $(\dfrac{1}{3}$ + $\dfrac{2}{3})$
= $\dfrac{5}{4}$ x $\dfrac{3}{3}$
= $\dfrac{5}{4}$ x 1
= $\dfrac{5}{4}$
e) $\dfrac{7}{2}$ x $\dfrac{5}{3}$ – $\dfrac{2}{3}$ x $\dfrac{7}{2}$
= $\dfrac{7}{2}$ x $(\dfrac{5}{3}$ – $\dfrac{2}{3})$
= $\dfrac{7}{2}$ x $\dfrac{3}{3}$
= $\dfrac{7}{2}$
f) 4 x 89 x 25
= (4 x 25) x 89
= 100 x 89
= 8900
@Yết gửi bạn nhé~~
HỌC TỐT~~
#NOCOPY
#NOTHINGISIMPOSSIBLE
a) $38. 67+33.38$
$=38(67+33)$
$=38.100=3800$
b) $49+785+51$
$=(49+51)+785$
$=100+785=885$
c) $87.134-34.87$
$=87(134-34)$
$=87.100=8700$
d) `5/4. 1/3+ 2/3. 5/4`
`=5/4.(1/3+2/3)`
`=5/4. 1=5/4`
e) `7/2. 5/3- 2/3. 7/2`
`=7/2(5/3-2/3)`
`=7/2.1=7/2`
f) $4.89.25$
$=(4.25).89$
$=100.89=8900$