Tính hợp lí:
a ) 10 17 − 5 13 + 7 17 − 8 13 ; b ) 30 51 − 20 52 + 14 34 − 56 91 − 2 c ) − 10 3 + 13 10 − 1 6 + 7 10 ; d ) 1 − 20 6 + 39 30 − 4 24 + 35 50
1/ Tìm số nguyên x
a) 2.x -18 = 10
b) 3.x + 26 = 5
c) I x-2 I = 0
2/ Tính hợp lí
a ) 18 .17 -3 .6.7
b) 54-6 (17 + 9)
c) 33. (17-5) -17 .(33-5)
Tính hợp lí
1) -145.(13 - 57) + 57.(10 -145)
2) 17.(15 - 16) + 16.( 17- 20)
3) -38.(25 - 4) + 25.(-4 + 38 )
4) 23.(145 - 17) - 145.(23 - 6)
5) 24.(15 - 4) + 4.(24 - 15)
6) 199.(15 - 17) - 199.(-17 + 5)
7) -39.(5 - 99) + 99.(10 - 39)
1 tính hợp lí
a. -5/18 + 32/45 - 9/10
b. 3/4 - (-5/8) + 9/4 - 3/16
c.11/125 - 17/18 - 5/7 + 4/9 + 17/14
d.-2 /5 - 3/10 - ( - 1/2)
Đây là phân số
a)\(\frac{-5}{18}+\frac{32}{45}-\frac{9}{10}\)
\(=\frac{-25}{90}+\frac{64}{90}-\frac{81}{90}\)
\(=-\frac{42}{90}=-\frac{7}{15}\)
b)\(\frac{3}{4}-\left(-\frac{5}{8}\right)+\frac{9}{4}-\frac{3}{16}\)
\(=\frac{3}{4}+\frac{5}{8}+\frac{9}{4}-\frac{3}{16}\)
\(=\frac{12}{16}+\frac{10}{16}+\frac{36}{16}-\frac{3}{16}\)
\(=\frac{58}{16}=\frac{29}{8}\)
c) \(\frac{11}{125}-\frac{17}{18}-\frac{5}{7}+\frac{4}{9}+\frac{17}{14}=\frac{11}{125}\)
d) \(\frac{-2}{5}-\frac{3}{10}-\left(-\frac{1}{2}\right)\)
\(=-\frac{2}{5}-\frac{3}{10}+\frac{1}{2}\)
\(=-\frac{4}{10}-\frac{3}{10}+\frac{5}{10}\)
\(=-\frac{2}{10}=-\frac{1}{5}\)
Tính hợp lí
1) \((\)\(\dfrac{7}{-18}\)+\(\dfrac{-5}{12}\)) -\(\dfrac{13}{-18}\)
2) \(\dfrac{-13}{17}\)+(\(\dfrac{13}{-21}\)+\(\dfrac{-4}{17}\))
3) ( \(\dfrac{13}{-10}\)-\(\dfrac{-4}{13}\))+\(\dfrac{11}{-10}\)
4) \(\dfrac{13}{17}\)\(\times\)\(\dfrac{4}{-5}\)+\(\dfrac{13}{17}\)\(\times\)\(\dfrac{-3}{4}\)
5) \(\dfrac{-5}{12}\)\(\times\)\(\dfrac{7}{-17}\)\(\times\)\(\dfrac{9}{-20}\)
6) \(\dfrac{5}{9}\)\(\times\)\(\dfrac{11}{23}\)+ \(\dfrac{11}{23}\)\(\times\)\(\dfrac{17}{9}\)\(-\)\(\dfrac{13}{9}\)\(\times\)\(\dfrac{11}{23}\)
\(1.\dfrac{-7}{18}+\dfrac{-5}{12}-\dfrac{-13}{18}\text{=}\left(\dfrac{-7}{18}-\dfrac{-13}{18}\right)+\dfrac{-5}{12}\text{=}\dfrac{1}{3}+\dfrac{-5}{12}\text{=}\dfrac{-1}{12}\)
\(2.\dfrac{-13}{17}+\dfrac{-13}{21}+\dfrac{-4}{17}\text{=}\left(\dfrac{-13}{17}+\dfrac{-4}{17}\right)+\dfrac{-13}{21}\text{=}-1+\dfrac{-13}{21}\text{=}\dfrac{-34}{21}\)
\(3.\dfrac{-13}{10}-\dfrac{-4}{13}+\dfrac{-11}{10}\text{=}\dfrac{-12}{5}-\dfrac{-4}{13}\text{=}\dfrac{-136}{65}\)
\(4.\dfrac{13}{17}\times\left(\dfrac{-4}{5}+\dfrac{-3}{4}\right)\text{=}\dfrac{13}{17}\times\dfrac{-31}{20}\text{=}\dfrac{-403}{340}\)
\(5.\left(\dfrac{-5}{12}\times\dfrac{-9}{20}\right)\times\dfrac{-7}{17}\text{=}\dfrac{3}{16}\times\dfrac{-7}{17}\text{=}\dfrac{-21}{272}\)
\(6.\dfrac{11}{23}\times\left(\dfrac{5}{9}+\dfrac{17}{9}-\dfrac{13}{9}\right)\text{=}\dfrac{11}{23}\times1\text{=}\dfrac{11}{23}\)
Thực hiện phép tính(tính hợp lí nếu có thể)
4/5+(-5)/4 -1/3+2/5-5/6 2/3-5/7.14/25 (2/5-5/6):8/15-(-1)^2
-3/13+(-7)/17+(-5)/19+(-10)/13+24/17+(-14)/19
\(\dfrac{4}{5}\)+\(\dfrac{-5}{4}\)=\(\dfrac{0}{4}\)
\(\dfrac{-1}{3}\)+\(\dfrac{2}{5}-\dfrac{5}{6}\)=\(\dfrac{-10}{30}+\dfrac{12}{30}-\dfrac{25}{30}\)=\(\dfrac{-23}{30}\)
\(\dfrac{2}{3}-\dfrac{5}{7}.\dfrac{14}{25}\)=\(\dfrac{2}{3}-\dfrac{2}{5}\)=\(\dfrac{10}{15}-\dfrac{6}{15}\)=\(\dfrac{4}{15}\)
a: \(=\dfrac{16-25}{20}=\dfrac{-9}{20}\)
b: \(=\dfrac{-10}{30}+\dfrac{12}{30}-\dfrac{25}{30}=-\dfrac{23}{30}\)
c: \(=\dfrac{2}{3}-\dfrac{1}{5}\cdot2=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{10-6}{15}=\dfrac{4}{15}\)
d: \(=\dfrac{12-25}{30}\cdot\dfrac{15}{8}-1=\dfrac{-13}{16}-1=\dfrac{-29}{16}\)
e: \(=\dfrac{-3}{13}-\dfrac{10}{13}-\dfrac{7}{17}+\dfrac{24}{17}-\dfrac{5}{19}-\dfrac{14}{19}=-1\)
bài 10 : Tính hợp lí :
a) ( 135 - 35 ) . ( - 37 ) + 37 . ( - 42 - 58 )
b) 12 . ( - 125 ) . 17
c) [ 3 . ( - 2 ) - ( - 8 ) ] . ( - 7 ) - ( - 2 ) . 5
ai làm được bài này tôi bái là sư phụ luôn ( phải giải thích một cách cụ thể chứ ko phải là bằng kết quả luôn đâu )
Tính hợp lí
a, 387 . 2694 + 7305 . 387 + 387
b, ( 5^16 + 16^5 ) ( 3^17 - 3^10 ) ( 2^4 - 4^2 )
c, ( 5^2007 - 5^2006 ) : ( 5^2005 . 5 )
a, 387 . 2694 + 7305 . 387 + 387
= 387 . ( 2694 + 7305 ) +387
= 387 . 9999 + 387
= 3869613 + 387
= 3870000
hai câu còn lại tự làm
/ Tính hợp lí
a ) 18 .17 -3 .6.7
b) 54-6 (17 + 9)
c) 33. (17-5) -17 .(33-5)
a/ 18.17-3.6.7
=18.6.3.(17-7)
=18.6.3.10
18.18.10
3240
a)=18.17-18.7
=18.(17-7)=18.10=180
b)=54-(6.17+6.9)=54-102-54=(54-54)-102=0-102=-102
c)=(33.17-33.5)-(17.33-17.5)=33.17-33.5-17.33+17.5=(33.17-17.33)-5.(33-17)=0-80=-80
tính hợp lí ( nếu có thể)
a)18.17-3*6*7
b)33.(17-5)-7(33-5)
c) (-4-14):(-3)
d)(-25).12(-4).10
a> 18.17-3.6.7
= 18.17-18.7
= 18 ( 17-7)
= 18.10 = 180
đi giải tiếp
Tính (một cách hợp lí): 33.(17 – 5) – 17(33 -5)
33.(17 – 5) – 17.(33 -5)
= 33. 17 – 33.5 – 17.33 + 17.5
= (33.17 – 33. 17) + ( 17.5 – 33.5)
= 0 + 5.(17- 33)
= 5.(- 16) = -80