Thực hiện phép tính:
\(A=\left(18.123+9.4567.2+3.5310.6\right):\left(1+4+7+10+...+55+58\right)-410\)
G=\(\frac{18.123+9.4567.2+3.5310.6}{1+4+7+10+...+55+58-410}\)
\(G=\frac{18.123+9.4567.2+3.5310.6}{1+4+7+...+55+58-410}\)
\(\rightarrow G=\frac{18.123+18.4567+18.5310}{\left(58+1\right).20\div2-410}\)
\(\rightarrow G=\frac{18.\left(123+4567+5310\right)}{590-410}\)
\(\rightarrow G=\frac{18.10000}{180}\)
\(\rightarrow G=\frac{180000}{180}\)
\(\rightarrow G=\frac{180.1000}{180}\)
\(\rightarrow G=1000\)
\(G=\left(18\cdot123+9\cdot4567\cdot2+3\cdot5310\cdot6\right)\div\left(1+4+7+10+55+58-410\right)\)
\(\left(58-1\right)\div3+1=20\)
\(G=\left(18\cdot123+9\cdot4567\cdot2+3\cdot5310\cdot6\right)\div\left[\left(58+1\right)\times20\div2-410\right]\)
\(G=180000\div180\)
\(G=1000\)
Tính nhanh : \(\left(18.123+9.436.2+3.5310.6\right):\left(1+4+7+|11|+100-410\right)\)
b, Ta có:
+) 1 + 4 +7 +……+ 100 = ( 1+100) + ( 4 + 97) +…….+ ( 49+ 52) = 101 . 34 = 1434
34 cặp
+) 1434 – 410 = 1024
+) ( 18 . 123 + 9 . 436 . 2 + 3 . 5310. 6 ) = 18 . ( 123 + 436 + 5310 )
= 18 . 5869 = 105642 ; Vậy A = 105642 : 1024 103,17
Tính giá trị biểu thức :
a, D= 1+2+4+8+16+...+1204
b, 18.123+9.4567.2+3.5310.6
c, E= 1+4+7+10+...+49+52+55+58-490
a,D=1+2+4+8+16+32+64+128+256+512+1024
D=(1+2)+4+8+16+32+64+128+256+512+1024
D=(4+4)+8+16+32+64+128+256+512+1024
D=(8+8)+16+32+64+128+256+512+1024
D=(16+16)+32+64+128+256+512+1024
D=(32+32)+64+128+256+512+1024
D=(64+64)+128+256+512+1024
D=(128+128)+256+512+1024
D=(256+256)+512+1024
D=(512+512)+1024
D=1024+1024
D=2048
b, 18.123+9.4567.2+3.5310.6
=18.123+(9.2).4567+(3.6).5310
=18.123+18.4567+18.5310
=18.(123+4567+5310)
=18.10000
=180000
c, E= 1+4+7+10+...+49+52+55+58-490
Dãy số trên có số số hạng là:(không tính số 490)
(58-1):(4-1).1+1=20(số)
E=(58+1).20:2-490=100
vậy E=100
Tính nhanh :
a) A = \(\dfrac{10\dfrac{1}{3}\left(26\dfrac{1}{3}-\dfrac{176}{7}\right)-\dfrac{12}{11}\left(\dfrac{10}{3}-1.75\right)}{\dfrac{5}{\left(91-0.25\right).\dfrac{60}{11}-1}}\)
b) ( 18.123+9.436.2+3.5310.6):(1+4+7+......+100-410)
giá trị rút gọn của A=\(\frac{18.123+9.4567.2+3.5310.6}{1+4+7+...+49+52+55+58-490}\)
tử số =18.123+9.4567.2+3.5310.6=18.123+18.4567+18.5310
=18(123+4567+5310)
=18.10000=180000
mẫu số = 1+4+7+....+49+52+55+58-490
=(1+58)+(4+55)+.....(28+31)-490
=59+59+59+...+59-490(10 so 59)
=100
suy ra A=180000:100=1800
Gia tri rut gon cua a = 18.123+9.4567.2+3.5310.6
1+4+7+10...+49+52+55+58-490 là
18.123+9.456.2+3.5310.6
1+ 4+ 7+10+ ...+ 55+58 -120
tính
a)\(\left(1-\frac{1}{1+2}\right).\left(1-\frac{1}{1+2+3}\right).\left(1-\frac{1}{1+2+3+4}\right).....\left(1-\frac{1}{1+2+3+...+20}\right)\)
b)\(\frac{\left(1+2+3+...+100\right).\left(12.3,4-6,86\right)}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{1}{6}}\)
c)(18.123+9.436.2+3.5310.6):1+4+7+...+100-410)
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