Tính nhanh giá trị mỗi phân số sau: a)15 .(\(\frac{212121}{434343}\) +\(\frac{333333}{353535}\) ) c)\(\frac{327.412+400}{328.412-12}\)
b) \(\frac{639\cdot7217721}{721\cdot639639}\)
a) 15.(212121/434343 +333333/353535).=?
b)639.721721 / 721.639639 =?
c)327.412+400 / 328.412-12 =?
a)=15.2154/1505
=6462/301
b)=461179719/138076
c,=134724+400/135136-12
=135124/135124
=1
Tính nhanh giá trị của mỗi phân số sau:
a,15 x (\(\frac{212121}{434343}\)+ \(\frac{333333}{353535}\))
b,\(\frac{\text{639 x 721721}}{721x639639}\)
c,\(\frac{327x412+400}{328x412-12}\)
d,9x(\(\frac{151515}{171717}\)+ \(\frac{131313}{181818}\))
ai đúng mình tick
a) \(15\times\left(\frac{212121}{434343}+\frac{333333}{353535}\right)=15\times\left(\frac{21\times10101}{43\times10101}+\frac{33\times10101}{35\times10101}\right)\)
\(=15\times\left(\frac{21}{43}+\frac{33}{35}\right)=\frac{6462}{301}\)
b) \(\frac{639\times721721}{721\times639639}=\frac{639\times721\times1001}{721\times639\times1001}=1\)
c) \(\frac{327\times412+400}{328\times412-12}=\frac{\left(328-1\right)\times412+400}{328\times412-12}=\frac{328\times412-412+400}{328\times412-12}\)
\(=\frac{328\times412-12}{328\times412-12}=1\)
d) \(9\times\left(\frac{151515}{171717}+\frac{131313}{181818}\right)=9\times\left(\frac{15\times10101}{17\times10101}+\frac{13\times10101}{18\times10101}\right)=9\times\left(\frac{15}{17}+\frac{13}{18}\right)\)
\(=9\times\frac{491}{306}=\frac{491}{34}\)
tinh nhanh
a,15.(\(\frac{212121}{434343}\).\(\frac{333333}{353535}\))
b,\(\frac{327.421+400}{328.421-12}\)
c,\(\frac{639.721721}{721.639639}\)
1. Tính nhanh
a)\(15\cdot\left(\frac{212121}{434343}+\frac{333333}{353535}\right)\)
b) \(\frac{639\cdot721721}{7217\cdot639639}\)
c) \(\frac{327\cdot412+400}{328\cdot412-12}\)
d) \(\frac{151515+131313}{171717+181818}\)
2. Cho phân số \(\frac{43}{56}\). Hãy tìm một số tự nhiên sao cho nếu đem tử số và mẫu số của phân số đã cho trừ đi số đó ta đc phân số mới có giá trị bằng \(\frac{3}{4}\).
A)15x2154/1505
=6462/301
B)=103/1031
C)=327/328+400/-12
=727/316
D)=4/5
Bai 2=4 ta thay mau so la 4 nen 43-4=39 va 56-4=52 ta se thay 39/52=3/4.
Tính nhanh:
a) 15 x ( 212121 / 434343 - 333333 / 353535 )
b) 327 x 412 + 400 / 328 x 412 + 12
Lưu ý: Dấu / là phân số
Giúp mình với nha
\(=15.\left(\frac{21.10101}{43.10101}-\frac{33.10101}{35.10101}\right)\)
\(=15.\left(\frac{21}{43}-\frac{33}{35}\right)\)
\(=15.\frac{-684}{1505}=\frac{-2052}{301}\)
ki hieu . la nhan do nha ban len cap 2 se thay dau x = .
Tính nhanh:
a) \(\frac{327.412+400}{328.412-12}\)
\(\frac{327\cdot412+400}{328\cdot412-12}=\frac{327\cdot412+400}{\left(327+1\right)\cdot412-12}=\)\(\frac{327\cdot412+400}{327\cdot412+1\cdot412-12}=\frac{327\cdot412+400}{327\cdot412+412-12}=\)\(\frac{327\cdot412+400}{327\cdot412+400}=\frac{1}{1}=1\)
\(\frac{327.412+400}{328.412-12}\) = \(\frac{328.412-412+400}{328.412-12}\)= \(\frac{328.412-\left[412-400\right]}{328.412-12}\) = \(\frac{328.412-12}{328.412-12}\) = 1
tính nhanh \(\frac{327.412+400}{328.412-12}\)
\(\frac{327\cdot412+400}{328\cdot412-12}\)
\(=\frac{327\cdot412+400}{\left(327+1\right)\cdot412-12}\)
\(=\frac{327\cdot412+400}{327\cdot412+\left(412-12\right)}\)
\(=\frac{327\cdot412+400}{327\cdot412+400}\)
\(=1\)
327.412+400 / 328.412-12
= 327.412+400 / (327+1).412-12
= 327.412+400 / 327.412+1.412-12
= 327.412+400 / 327.412+412-12
= 400/412-12
= 400/400
= 1
tính nhanh
15*(212121/434343+333333/353535
15 x (\(\frac{212121}{434343}+\frac{333333}{3535335}\)) = 15 x ( \(\frac{21.10101}{43.10101}+\frac{33.10101}{35.10101}\))
= 15 x ( \(\frac{21}{43}+\frac{33}{35}\)) = 5 x 3 x \(\frac{735}{1505}+\frac{1419}{1505}\)= 5 x 3 x \(\frac{2154}{1505}\)= \(\frac{6462}{301}\)
15 x ( 212121/434343 + 333333/353535)
639 x 721721/ 721 x 639639
327 x 412 + 400 / 328 - 412 -12
\(a)15.\left(\dfrac{212121}{434343}+\dfrac{333333}{353535}\right)\)
\(=15.\left(\dfrac{21}{43}+\dfrac{33}{35}\right)\)
\(=15.\dfrac{2154}{1505}\)
\(=\dfrac{6462}{301}\)