Tính
75%+0,264+0,85+1/4+736/1000+15%-2 1/2
Tính nhanh hộ mik nha!
A=1/2×1/3+1/3×1/4+1/4×1/5+1/5×1/6
Và bài này nữa
15÷x=0,85+0,35
1/2x3+1/3x4+1/4x5+1/5x6
= 1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6
=1/2-1/6
=1/3
15:x= 0.85+0.35
15:x= 1,2
x= 15:1,2
x= 12,5
nha bn, mk nghĩ vậy
a) \(A=\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(=\frac{1}{2}-\frac{1}{6}\)
\(=\frac{1}{3}\)
b) \(15\div x=0,85+0,35\)
\(\Rightarrow15\div x=1,2\)
\(\Rightarrow x=15\div1,2\)
\(\Rightarrow x=12,5\)
Vậy \(x=12,5\)
a ) 2,137 . 175 - 2,137 . 75
b) 2,8 . 225 + 72 . 22.5
c) 15 . 91,5 + 150 . 0,85
d) 1,43 . 141 - 1,43 . 4
a) 2.137 . 175 - 2.137 . 75
= 2.137 . ( 175 - 75 )
= 2.137 . 100
= 213.7
b) 2.8 . 225 + 72 . 22.5
= 630 + 1620
= 2250
c) 15 . 91.5 + 150 . 0.85
= 1372.5 + 127.5
= 1500
d) 1.43 . 141 - 1.43 . 4
= 1.43 . ( 141 - 4 )
= 1.43 . 137
= 195.91
Tính
a) \(\frac{\left(5\frac{4}{45}-4\frac{1}{15}\right)}{1\frac{1}{3}}.30-\frac{4,25:0,85+1:0,5}{\left(5,36-4,06\right):2,6+6,5}\)
a)\(\frac{\left(5\frac{4}{45}-4\frac{1}{15}\right)}{1\frac{1}{3}}.30-\frac{4,25:0.85+1:0.5}{\left(5,36-4,06\right):2,6+6,5}\)
\(=23-1\)
\(=22\)
\(\frac{\left(5\frac{4}{45}-4\frac{1}{15}\right)}{1\frac{1}{3}}.30-\frac{4,25\div0,85+1\div0,5}{\left(5,36-4,06\right)\div2,6+6,5}\)
\(=1\frac{1}{45}\div\frac{4}{3}.30-\frac{\left(4,25\div0,85\right)+\left(1\div0,5\right)}{1,3\div2,6+6,5}\)
\(=\frac{46}{45}\div\frac{4}{3}.30-\frac{5+2}{0,5+6,5}=\frac{23}{30}.30-\frac{7}{7}\)
\(=23-1=22\)
(toán) ghi rõ cả cách tính nha
bài 1:tính nhanh
a) 10566 + 8074 + 9444 + 926 + 1000 b) 576 + 789 + 467 + 111
bài 2 : tính nhanh
a) 5/7 + 7/3 + 19/13 + 6/5 + 7/9 + 9/5 b) 1/15 + 2/15 + 3/15 + 4/15 + 5/15 + 6/15 + 7/15 + 8/15 + 9/15
bài 3 :Tính bằng cách thuận tiện nhất
tính bằng cách thuận tiện nhất
a) 417, 325 + 84,76 + 6,676 b) 38, 077 + 9,012 + 16,023 + 8,088 c) 2,9 + 1,71 + 0,29 + 2,1 + 1,3
bài 4: tìm hai số có tổng bằng 1149, biết rằng nếu giữ nguyên số lớn và gấp đôi số bé lên ba lần ta được tổng mới bằng 2061( ghi bài giải)
1.So sánh :
a) 2^75 và 128^25
b) 125^12 và 25^15
c) 7^1000 và 10^500
d) 31^11 và 17^4
a) Ta có:
12825 = (26)25 = 26.25 = 2150
Vì 150 > 75 nên 2150 > 275
Hay 275 < 12825
b) Ta có:
12512 = (53)12 = 536
2515 = (52)15 = 530
Vì 36 > 30 nên 536 > 530
Hay 12512 > 2515
c) Ta có:
71000 = 72.500 = (72)500 = 49500
Vì 49 > 10 nên 49500 > 10500
Hay 71000 > 10500
d) Ta có:
31 > 17 và 11 > 4
\(\Rightarrow\) 3111 > 174
Sửa lại câu a) nè:
12825 = (27)25 = 27.25 = 2175
Vì 175 > 75 nên 2175 > 275
Hay 275 < 12825
tính nhanh D=2009^(1000-1^3)(1000-2^3)...(1000-15^3)
D = 2009^(1000 - 1^3)...(1000-10^3)...(1000-15^3)
= 2009^(1000 - 1^3) .....0.(1000-15^3)
= 2009^0
= 1
Bài 442: Tính hợp lý:
1. 1/3 . 4/5 + 1/3 . 6/5 - 1/3
2. 3/7 . 9/26 - 1/14 . 1/13
3. 15(1/5 - 7/15 + 17/3)
4. 38(2và1/19 - 5và7/38)
5. 75( - 4/25 + 7và1/15 - 5và7/75)
\(1)\frac{1}{3}.\frac{4}{5}+\frac{1}{3}.\frac{6}{5}-\frac{1}{3}\)
\(=\frac{1}{3}\left(\frac{4}{5}+\frac{6}{5}\right)\)
\(=\frac{1}{3}.2\)
\(=\frac{2}{3}\)
\(1)\)\(\frac{1}{3}.\frac{4}{5}+\frac{1}{3}.\frac{6}{5}-\frac{1}{3}\)
\(=\frac{1}{3}.\left(\frac{4}{5}+\frac{6}{5}-1\right)\)
\(=\frac{1}{3}.\left(\frac{4}{5}+\frac{6}{5}-\frac{5}{5}\right)\)
\(=\frac{1}{3}.1\)
\(=\frac{1}{3}\)
\(2)\)\(\frac{3}{7}.\frac{9}{26}-\frac{1}{14}.\frac{1}{13}\)
\(=\frac{1}{7}.\frac{27}{26}-\frac{1}{7}.\frac{1}{26}\)
\(=\left(\frac{27}{26}-\frac{1}{26}\right).\frac{1}{7}\)
\(=1.\frac{1}{7}\)
\(=\frac{1}{7}\)
\(3)\)\(15\left(\frac{1}{5}-\frac{7}{15}+\frac{17}{3}\right)\)
\(=3-7+85\)
\(=81\)
\(4)\)\(38\left(2\frac{1}{19}-5\frac{7}{38}\right)\)
\(=38\left(\frac{39}{19}-\frac{197}{38}\right)\)
\(=78-197\)
\(=-119\)
\(5)\)\(75\left(\frac{-4}{25}+7\frac{1}{15}-5\frac{7}{75}\right)\)
\(=75\left(\frac{-4}{25}+\frac{106}{15}-\frac{382}{75}\right)\)
\(=-12+530-382\)
\(=136\)
Ddaeng
1, \(\frac{1}{3}.\frac{4}{5}+\frac{1}{3}.\frac{6}{5}-\frac{1}{3}\)
\(=\frac{1}{3}.\left(\frac{4}{5}+\frac{6}{5}\right)-\frac{1}{3}\)
\(=\frac{1}{3}.2-\frac{1}{3}\)
\(=\frac{2}{3}-\frac{1}{3}\)
\(=\frac{1}{3}\)
2, \(\frac{3}{7}.\frac{9}{26}-\frac{1}{14}.\frac{1}{13}\)
\(=\frac{1}{7}.3.\frac{9}{26}-\frac{1}{7}.\frac{1}{2}.\frac{1}{13}\)
\(=\frac{1}{7}.\frac{27}{26}-\frac{1}{7}.\frac{1}{26}\)
\(=\frac{1}{7}.\left(\frac{27}{26}-\frac{1}{26}\right)\)
\(=\frac{1}{7}.1\)
\(=\frac{1}{7}\)
3, \(15.\left(\frac{1}{5}-\frac{7}{15}+\frac{17}{3}\right)\)
\(=15.\frac{1}{5}-15.\frac{7}{15}+15.\frac{17}{3}\)
\(=3-7+85\)
\(=81\)
4, \(38.\left(2\frac{1}{19}+5\frac{7}{38}\right)\)
\(=38.\left(\frac{39}{19}+\frac{197}{38}\right)\)
\(=38.\frac{39}{19}+38.\frac{197}{38}\)
\(=78+197\)
\(=275\)
5, \(75.\left(\frac{-4}{25}+7\frac{1}{15}-5\frac{7}{75}\right)\)
\(=75.\left(\frac{-4}{25}+\frac{106}{15}-\frac{382}{75}\right)\)
\(=75.\frac{-4}{25}+75.\frac{106}{15}-75.\frac{382}{75}\)
\(=-12+530-382\)
\(=136\)
Tính nhanh
(1000-1^3).(1000-2^3).(1000-3^3). ... .(1000-15^3)
=(1000-1^3).(1000-2^3).(1000-3^3)......(1000-10^3)....(1000-15^3)
=(1000-1^33).(1000-2^3).(1000-33).......0..........(1000-15^3) =0
\(\left(1000-1^3\right)\left(1000-2^3\right)\left(1000-3^3\right)...\left(1000-15^3\right)\)
\(=\left(1000-1^3\right)\left(1000-2^3\right)...\left(1000-10^3\right)...\left(1000-15^3\right)\)
\(=\left(1000-1^3\right)\left(1000-2^3\right)...\cdot0\cdot...\left(1000-15^3\right)\)
\(=0\)
Bài 4: Tính nhanh: a) 2004^2- 16
b) 892^2+ 892 . 216 + 108^2
c) 36^2 + 26^2 – 52 . 36
d) (10,2 . 9,8 – 9,8 . 0,2) + (10,22 –10,2 . 0,2 )
e) 20,03 . 45 + 20,03 . 47 + 20,03 . 8
g) 15,75 . 175 – 15, 75 . 55 – 15, 75 . 20
h/ A=57^2+114.43+43^2
i/ B=5^4.3^4-(15^2-1).(15^2+1)
k) C=50^2-49^2+48^2-47^2+……+2^2-1^1
a: \(2004^2-16=2000\cdot2008=4016000\)
b: \(892^2+892\cdot216+108^2=1000^2=1000000\)
c: \(36^2-52\cdot36+26^2=10^2=100\)