tính bằng cách hợp lí:
a/ (-31).13+(-91).5+131+(-5).9
Tính: (-31).13 + (-91).5 + 131 + (-5).9
(-31).13 + (-91).5 + 131 + (-5).9
(-31+-91+-5)+(13+5+131+9)
-127+158
31
hấn giải sai rồi nguyenmanhtrung à
tính: a/(-31).13+(-91).5+131+(-5).9
b/[-2008.57+1004.(-86)]:[32.74+16.(-48)]
(-31).13+(-91).5+131+(-5)+9
= (-403)+(-455)+(-5)+9
= -863+9
=-854
Tính hợp lí :
(-31).13+(-91).5+131+(-5).9
ai giải nhanh mik tick cho nha,giúp mik đi,khẩn cấp lắm!
Tính một cách hợp lí:
a) \(\dfrac{27}{13}-\dfrac{106}{111}+\dfrac{-5}{111};\)
b) \(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19};\)
c) \(\dfrac{5}{17}-\dfrac{25}{31}+\dfrac{12}{17}+\dfrac{-6}{31}.\)
\(a.\)
\(\dfrac{27}{13}-\dfrac{106}{111}+-\dfrac{5}{111}=\dfrac{27}{13}-\dfrac{106}{111}-\dfrac{5}{111}=\dfrac{27}{13}-\left(\dfrac{106+6}{111}\right)=\dfrac{27}{13}-1=\dfrac{14}{13}\)
\(b.\)
\(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+\dfrac{7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+1=\dfrac{23}{11}\)
\(c.\)
\(\dfrac{5}{17}-\dfrac{25}{31}+\dfrac{12}{17}+-\dfrac{6}{31}=\left(\dfrac{5}{17}+\dfrac{12}{17}\right)-\left(\dfrac{25}{31}+\dfrac{6}{31}\right)=1-1=0\)
a) \(\dfrac{27}{13}-\dfrac{106}{111}+\dfrac{-5}{111}=\dfrac{27}{13}+\left(\dfrac{-106}{111}+\dfrac{-5}{111}\right)=\dfrac{27}{13}+-1=\dfrac{14}{13}\)
b) \(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+\left(\dfrac{7}{19}+\dfrac{12}{19}\right)=\dfrac{12}{11}+1=\dfrac{23}{11}\)
c)\(\dfrac{5}{17}-\dfrac{25}{31}+\dfrac{12}{17}+\dfrac{-6}{31}=\left(\dfrac{5}{17}+\dfrac{12}{17}\right)+\left(\dfrac{-25}{31}+\dfrac{-6}{31}\right)=1+-1=0\)
1) Tính bằng cách hợp lí:
a) -4/7 + 3/7 + -4/5 + 4/7 - 2334
b) 5/13 + 4/19 + -8/13 + 15/19 + 456
2) Tìm x biết
a) 3/7 - x = -11/14
b) x - 4/9 = -12/9 + 3/18
GIÚP MÌNH VỚI, MIK CẦN GẤP LẮM
1:
a: \(=\dfrac{-4}{7}+\dfrac{4}{7}+\dfrac{3}{7}-\dfrac{23}{34}-\dfrac{4}{5}=\dfrac{3}{7}-\dfrac{23}{34}-\dfrac{4}{5}=-\dfrac{1247}{1190}\)
b:
Sửa đề: \(\dfrac{-5}{13}+\dfrac{4}{19}+\dfrac{-8}{13}+\dfrac{15}{19}+\dfrac{45}{6}\)
\(=\dfrac{-5}{13}-\dfrac{8}{13}+\dfrac{4}{19}+\dfrac{15}{19}+\dfrac{45}{6}=\dfrac{9}{2}\)
Tính giá trị các biểu thức sau một cách hợp lí:
A = 5/11 . 5/7 + 5/11 . 2/7 + 6/11
B= 3/13 . 6/11 + 3/13 . 9/11 – 3/13 . 4/11
C= ( 12/16 – 31/22 + 14/91 ) . (1/2 – 1/3 – 1/6 )
Hãy giúp mk
\(A=\dfrac{5}{11}.\dfrac{5}{7}+\dfrac{5}{11}.\dfrac{2}{7}+\dfrac{6}{11}=\dfrac{5}{11}\left(\dfrac{5}{7}+\dfrac{2}{7}\right)+\dfrac{6}{11}=\dfrac{5}{11}.1+\dfrac{6}{11}=\dfrac{5}{11}+\dfrac{6}{11}=\dfrac{11}{11}=1\)
\(B=\dfrac{3}{13}.\dfrac{6}{11}+\dfrac{3}{13}.\dfrac{9}{11}-\dfrac{3}{13}.\dfrac{4}{11}=\dfrac{3}{13}\left(\dfrac{6}{11}+\dfrac{9}{11}-\dfrac{4}{11}\right)=\dfrac{3}{13}.1=\dfrac{3}{13}\)
\(C=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right)\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{6}\right)=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right)\left(\dfrac{3}{6}-\dfrac{2}{6}-\dfrac{1}{6}\right)=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right).0=0\)
Tổng (hiệu) sau là số nguyên tố hay hợp số?
a) 5 . 31 . 19 . 101 + 62 . 131 . 1989 . 17;
b) 23 . 161 . 121 . 91 – 13 . 157 . 22 . 37.
a) 5.31.19.101+62.131.1989.17
=274 926 631 => là số nguyên tố.
b) 23.161.121.91-13.157.22.37
= 39 112 359 => là hợp số.
a) 5 . 31 . 19 . 101 + 62 . 131 . 1989 . 17
= 5 . 31 . 19 . 101 + 31 . 2 . 131 . 1989 . 17
= 31 . (5 . 19 . 101 + 2 . 131 . 1989 . 17) chia hết cho 31 => 31 . (5 . 19 . 101 + 2 . 131 . 1989 . 17) là hợp số => 5 . 31 . 19 . 101 + 62 . 131 . 1989 . 17 là hợp số.
Tổng (hiệu) sau là số nguyên tố hay hợp số?
a) 5 . 31 . 19 . 101 + 62 . 131 . 1989 . 17;
b) 23 . 161 . 121 . 91 – 13 . 157 . 22 . 37.
Tính bằng cách hợp lí:
a)A=39/91 +35/40 +60/105 -15/8
b)B=1/2 +1/3 +4/5 +1/6 +3/8 -7/40
Giúp tớ với a,tớ đg cần gấp aaa!Cảm ơn trc a
a: \(=\dfrac{3}{7}+\dfrac{7}{8}+\dfrac{4}{7}-\dfrac{15}{8}=1-1=0\)
b: \(=\dfrac{1}{2}+\dfrac{4}{5}+\dfrac{3}{8}-\dfrac{7}{40}+\dfrac{1}{2}\)
\(=1+\dfrac{32+15-7}{40}=1+1=2\)