Tính:
7 x 5 + 15
7 x 9 +17
Tính giá trị biểu thức sau bằng 1 cách hợp lí
C1:
a, 3.7.23 - 21 . (- 17)
b, 7.6.3 -7.[(-34)+18]
c, 71.64+32 .(-7)-13.32
d, 13.(23-17)-13.(23+17)
e, (29-9). (-9)+ (-13-7).21
g, (-157).(127-316)-127.(316-157)
Helpppppppp●
a, 3.7.23 - 21.(-17)
= 21.23 + 21.17
= 21.(23 + 17)
= 21.40
= 840
b, 7.6.3 - 7.[(-34) + 18)]
= 7.18 - 7.18 + 34.7
= 34.7
= 238
c, 71.64 + 32.(-7) - 13.32
= 71. 32 . 2 - 7.32 - 32. 13
= 32.(71.2 - 7 - 13)
= 32. (142 - 20)
= 32.122
= 3904
d, 13.(23 - 17) - 13.(23 + 17)
= 13.23 - 13.17 - 13.23 - 13.17
= (13.23 - 13.23) - (13.17 + 13.17)
= - 2.13.17
= - 26.17
= -442
e, (29 - 9).(-9) + (-13 - 7).21
= 20.(-9) - 20.21
= -20.(9 + 21)
= -20.30
= - 600
257-(3x+25)=157
x-140:35=270
23-(x:13)=18
9(x+5)-13=671
9(4x)-13=24
(x-5)-34:17=1
.(2x-7). 3=3 dấu chấm là nhân nhé
(3x-5):2=4.5
9.(x+3)-20=5+4.5
70-(2x-50)=0
8.5-(x+7)=3.10
17-(x:12)=17
32.9-8x=100.2
9.(x+5)-13=671
5.(x+5)-2.24=2.26
4.(x+1)-28=3.4
giúp mk mk tích cho
\(257-\left(3x+25\right)=157\)
\(3x+25=257-157\)
\(3x+25=100\)
\(3x=75\)
\(x=25\)
vay \(x=25\)
\(x-140:35=270\)
\(x-4=270\)
\(x=274\)
vay \(x=274\)
\(23-\left(x:13\right)=18\)
\(\frac{x}{13}=5\)
\(\frac{x}{13}=\frac{65}{13}\)
\(\Rightarrow x=65\)
vay \(x=65\)
\(9\left(x+5\right)-13=671\)
\(9x+45=684\)
\(9x=639\)
\(x=71\)
vay \(x=71\)
\(9\left(4x\right)-13=24\)
\(36x=37\)
\(x=\frac{37}{36}\)
vay \(x=\frac{37}{36}\)
\(\left(x-5\right)-34:17=1\)
\(\left(x-5\right)-2=1\)
\(x-5=3\)
\(x=8\)
vay \(x=8\)
\(\left(2x-7\right).3=3\)
\(2x-7=1\)
\(2x=8\)
\(x=4\)
vay \(x=4\)
\(\left(3x-5\right):2=4.5\)
\(\left(3x-5\right):2=20\)
\(3x-5=10\)
\(3x=15\)
\(x=5\)
vay \(x=5\)
con lai lam tuong tu
mk moi tay roi nen ban tu lam vay
Dùng tính chất phân phối của phép nhân với phép cộng để tính : a, 157.17 - 157 . 7 b, 5. ( -3 +2 ) - 7. ( 5-4) c, 17. ( -84) + 17. ( -16) d, -145 . ( 13 - 57 ) + 57 . ( 10- 145 ) e, 199. ( 15-17) - 199. ( -17 + 5)
\(a,157.17-157.7=157\left(17-7\right)=1570\)
\(b,5.\left(-3+2\right)-7.\left(5-4\right)=-5-7=-12\)
\(c,17.\left(-84\right)+17\left(-16\right)=17\left[\left(-84\right)+\left(-16\right)\right]=-1700\)
\(d,-145.\left(13-57\right)+57.\left(10-145\right)=6380-7695=-1315\)
\(e,199.\left(15-17\right)-199.\left(-17+5\right)=199.10=1990\)
Tính bằng cách thuận tiên nhất:
1):(3/4 x 5/97 + 1/9 x 13/47) x (1/5 - 7/25 x 5/7)
2): 8/17 x 4/15 + 8/17 x 22/15 - 8/15 x 9/17
3): 2021/2 x 1/3 + 4042/4 x 1/5 + 6063/3 x 22/15
4); 4/7 x 2/13 + 8/13 :7/4 + 4/7 : 13/2 + 4/7 x 1/13
5): 2022 x 2021 - 1/ 2021 + 2022 x 2020
6): 18 x 123 + 9 x 4567 x 2 + 3 x 5310 x 6 / (2 + 4 + 6 + 8 + ...+20 + 22) + 48
7): A= 2021 x 2021 x 202020 - 2020 x 2020 x 20212021 / 2020 x 20192019
1) Ta có: \(\left(\dfrac{3}{4}\cdot\dfrac{5}{97}+\dfrac{1}{9}\cdot\dfrac{13}{47}\right)\cdot\left(\dfrac{1}{5}-\dfrac{7}{25}\cdot\dfrac{5}{7}\right)\)
\(=\left(\dfrac{3}{4}\cdot\dfrac{5}{97}+\dfrac{1}{9}\cdot\dfrac{13}{47}\right)\cdot\left(\dfrac{1}{5}-\dfrac{1}{5}\right)\)
=0
2) Ta có: \(\dfrac{8}{17}\cdot\dfrac{4}{15}+\dfrac{8}{17}\cdot\dfrac{22}{15}-\dfrac{8}{15}\cdot\dfrac{9}{17}\)
\(=\dfrac{8}{17}\left(\dfrac{4}{15}+\dfrac{22}{15}-\dfrac{9}{15}\right)\)
\(=\dfrac{8}{17}\cdot\dfrac{15}{15}=\dfrac{8}{17}\)
3) Ta có: \(\dfrac{2021}{2}\cdot\dfrac{1}{3}+\dfrac{4042}{4}\cdot\dfrac{1}{5}+\dfrac{6063}{3}\cdot\dfrac{22}{15}\)
\(=\dfrac{2021}{2}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)+2021\cdot\dfrac{22}{15}\)
\(=\dfrac{2021}{2}\cdot\dfrac{8}{15}+\dfrac{2021}{2}\cdot\dfrac{44}{15}\)
\(=\dfrac{2021}{2}\cdot\dfrac{52}{15}\)
\(=\dfrac{52546}{15}\)
4) Ta có: \(\dfrac{4}{7}\cdot\dfrac{2}{13}+\dfrac{8}{13}:\dfrac{7}{4}+\dfrac{4}{7}:\dfrac{13}{2}+\dfrac{4}{7}\cdot\dfrac{1}{13}\)
\(=\dfrac{4}{7}\left(\dfrac{2}{13}+\dfrac{8}{13}+\dfrac{2}{13}+\dfrac{1}{13}\right)\)
\(=\dfrac{4}{7}\)
Tính hợp lí
2/9 x 5/17 + 2/9 x 12/7 - 1/9
\(\dfrac{2}{9}\cdot\dfrac{5}{17}+\dfrac{2}{9}\cdot\dfrac{12}{17}-\dfrac{1}{9}\\ \\ \\ =\dfrac{2}{9}\cdot\left(\dfrac{5}{17}+\dfrac{12}{17}\right)-\dfrac{1}{9}\\ \\ \\ =\dfrac{2}{9}\cdot1-\dfrac{1}{9}\\ \\ \\ =\dfrac{2}{9}-\dfrac{1}{9}=\dfrac{1}{9}\)
Bạn ơi 12/7 chứ ko phải 12/17 đâu nhé
Câu 1: Tìm x:
a) 2/5× x = 8/7: x =4/5
Câu 2: Tính bằng cách thuận tiện nhất
5/9× 8/17 + 4/9 × 8/17
Câu 2:Đáp số là 8/17 nhé
(5/9+4/9)x8/17
=>1x8/17=8/17
Câu 1: Tìm x:
a) 2/5× x =(thiếu đề)
8/7: x =4/5
x=8/7:4/5
x=10/7
Câu 2: Tính bằng cách thuận tiện nhất
5/9× 8/17 + 4/9 × 8/17
=(5/9+4/9)x8/17
=1x8/17=8/17
Câu 1: Tìm x:
a) 2/5× x = 4 8/7: x =4/5
Câu 2: Tính bằng cách thuận tiện nhất
5/9× 8/17 + 4/9 × 8/17
Câu 1
\(a,\dfrac{2}{5}\times x=4\\ x=4:\dfrac{2}{5}=10\\ b,7:x=\dfrac{4}{5}\\ x=\dfrac{4}{5}\times7=\dfrac{28}{5}\)
Câu 2
\(=\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\times\dfrac{8}{17}=1\times\dfrac{8}{17}=\dfrac{8}{17}\)
Câu 1: Tìm x:
a) 2/5× x = 4
x=4 : 2/5
x=10
8/7: x =4/5
x=8/7:4/5
x=10/7
Câu 2: Tính bằng cách thuận tiện nhất
5/9× 8/17 + 4/9 × 8/17
=(5/9+4/9)x8/17
=1x8/17=8/17
\(5/9× 8/17 + 4/9 × 8/17 =>(5/9+4/9)×8/17 =>1 ×8/17=8/17\)
thực hiện phép tính
2/9 x 5/17 +2/9 x 12/7 + 7/9
giúp mk vs
= \(\frac{2}{9}\left(\frac{5}{17}+\frac{12}{17}\right)+\frac{7}{9}\)
= \(\frac{2}{9}\times1+\frac{7}{9}\)
= \(1\)
xin tiick
1. 27 x 75 + 25 x 75 - 150
2. 15 x 23 + 15 x 37 + 40 + 15
3. 4 x 9 x 14 + 3 x 17 x 12 + 2 x 69 x 18
4. 32 x ( 157 + 43) + 68 x ( 157 + 43)
1: \(=75\left(27+25-2\right)=75\cdot50=3750\)
2: \(=15\left(23+37\right)+55=15\cdot60+55=955\)
3: \(=36\cdot14+36\cdot17+36\cdot69\)
\(=36\cdot100=3600\)
4: \(=200\cdot\left(32+68\right)=200\cdot100=20000\)