Tính nhanh:
\(\dfrac{75}{100}+\dfrac{3}{4}\cdot29+75\%\cdot30+0.75\cdot40\)
Tính bằng cách nhanh nhất: 75/100+ 3/4 ×29 +75% ×30 + 0.75 ×40
= ( 75 : 100 ) + ( 3: 4 ) + ( 75 : 100 ) x 29 x 30 + 0,75 x 40
= 0,75 + 0,75 + 0,75 x 29 x30 + 0,75 x 40
= 0,75 x ( 29 + 30 + 40 )
= 0,75 x 100
= 75
tham khảo:
= ( 75 : 100 ) + ( 3: 4 ) + ( 75 : 100 ) x 29 x 30 + 0,75 x 40
= 0,75 + 0,75 + 0,75 x 29 x30 + 0,75 x 40
= 0,75 x ( 29 + 30 + 40 )
= 0,75 x 100
= 75
75/100 + 3/4 x 29 +75% x30 + 0.75 x 40 =?
Tham khảo:
75/100 + 3/4 x 29 + 75% x 30 + 0,75 x 40
= 0,75 + 0,75 x 29 + 0,75 x 30 + 0,75 x 40
= 0,75 x (1 + 29 + 30 + 40)
= 0,75 x 100
= 75
Tính :
a, \(\dfrac{3\cdot13-13\cdot18}{15\cdot40-80}\);
b, \(\dfrac{18\cdot34+\left(-18\right)\cdot124}{-36\cdot17+9\cdot\left(-52\right)}\);
c, \(\dfrac{\dfrac{3}{41}-\dfrac{12}{47}+\dfrac{27}{53}}{\dfrac{4}{41}-\dfrac{16}{47}+\dfrac{36}{53}}+\dfrac{-0,25\cdot\dfrac{-2}{3}-0,75:\left(\dfrac{-1}{2}+\dfrac{2}{3}\right)}{\left|-1\dfrac{1}{2}\right|\cdot\left(\dfrac{-2}{3}-75\%:\dfrac{3}{-2}\right)}\).
a: \(=\dfrac{13\left(3-18\right)}{40\left(15-2\right)}=\dfrac{13}{15-2}\cdot\dfrac{-15}{40}=\dfrac{-3}{8}\)
b: \(=\dfrac{18\left(34-124\right)}{36\left(-17-13\right)}=\dfrac{1}{2}\cdot\dfrac{-90}{-30}=\dfrac{3}{2}\)
c: \(=\dfrac{3\left(\dfrac{1}{41}-\dfrac{4}{47}+\dfrac{9}{53}\right)}{4\left(\dfrac{1}{41}-\dfrac{4}{47}+\dfrac{9}{53}\right)}+\dfrac{\dfrac{-1}{4}\cdot\dfrac{-2}{3}-\dfrac{3}{4}:\dfrac{1}{6}}{\dfrac{3}{2}\cdot\left(\dfrac{-2}{3}-\dfrac{3}{4}\cdot\dfrac{-2}{3}\right)}\)
\(=\dfrac{3}{4}+\dfrac{\dfrac{2}{12}-\dfrac{9}{2}}{\dfrac{3}{2}\cdot\dfrac{-1}{6}}=\dfrac{3}{4}+\dfrac{-13}{3}:\dfrac{-3}{12}=\dfrac{3}{4}+\dfrac{13}{3}\cdot\dfrac{12}{3}\)
\(=\dfrac{3}{4}+\dfrac{156}{9}=\dfrac{217}{12}\)
\(\dfrac{3}{4}\) x 36 + 75% x 23 + \(\dfrac{75}{100}\) + 0,75 x 40
= ..... x 36 + ....... x 23 + ..... + 0,75 x 40
= ..... x ( 36 + 23 + 1 + ..... )
= ..... x 100
= .....
75/100 + 3/4 x 29 +75% x30 + 0.75 x 40 =?
tối đa 2 cách:3
`@Neo`
`75/100 + 3/4 xx 29 +75% xx 30 + 0,75 xx 40 `
`=75/100+3/4xx29+75/100xx30+3/4xx40`
`=75/100+75/100xx29+75/100xx30+75/100xx40xx1`
`=75/100xx(29+1+30+40)`
`=75/100xx100`
`=7500/100=75/1=75`
__________________________________________
`75/100 + 3/4 xx 29 +75% xx 30 + 0,75 xx 40 `
`=75/100+3/4xx29+75/100xx30+3/4xx40`
`=3/4+3/4xx29+75/100xx30+3/4xx40xx1`
`=3/4xx(29+1+30+40)`
`=3/4xx100`
`=300/4=75/1=75`
________________________________________
`75/100 + 3/4 xx 29 +75% xx 30 + 0,75 xx 40 `
`=0,75+0,75×29+0,75×30+0,75×40`
`=0,75×(1+29+30+40)`
`=0,75xx100`
`=75`
`75/100+3/4xx29+75%xx30+0,75xx40`
`=3/4+3/4xx29+3/4xx30+3/4xx40`
`=3/4xx(1+29+30+40)`
`=3/4xx100=75`
Thực hiện phép tính, tính nhanh nếu có thể
a, \(\dfrac{7}{13}\) + \(\dfrac{12}{13}\) + \(\dfrac{6}{-13}\)
b, ( \(\dfrac{4}{5}\) + \(\dfrac{1}{2}\) ) x ( \(\dfrac{6}{13}\) - 2 )
c, 75% : \(\dfrac{1}{2}\) - \(2\dfrac{1}{2}\) x ( \(-1\dfrac{1}{3}\) )
d, 0,375 x \(1\dfrac{3}{5}\) + 60% x \(\dfrac{2}{7}\) + \(\dfrac{3}{5}\) x \(\dfrac{5}{7}\)
e, \(\dfrac{-5}{6}\) x \(\dfrac{7}{13}\) + \(\dfrac{19}{13}\) : \(\dfrac{6}{-5}\) + \(\dfrac{2}{5}\)
f, 1,25 x \(\dfrac{7}{9}+\dfrac{5}{4}x\dfrac{15}{9}-1\dfrac{1}{4}:\dfrac{19}{3}\)
a: \(=\dfrac{7+12-6}{13}=1\)
b: \(=\dfrac{13}{10}\cdot\dfrac{6-26}{13}=\dfrac{-20}{10}=-2\)
c: \(=\dfrac{3}{4}\cdot2-\dfrac{5}{2}\cdot\dfrac{-4}{3}=\dfrac{3}{2}+\dfrac{20}{6}=\dfrac{3}{2}+\dfrac{10}{3}=\dfrac{29}{6}\)
d: \(=\dfrac{3}{8}\cdot\dfrac{8}{5}+\dfrac{3}{5}\cdot\dfrac{2}{7}+\dfrac{3}{5}\cdot\dfrac{5}{7}=\dfrac{3}{5}+\dfrac{3}{5}=\dfrac{6}{5}\)
Bài 4. Trên tia Ox lấy điểm A và B sao cho OA = 8cm, OB = 12cm.
a, Điểm A có nằm giữa hai điểm O và B không? Vì sao? Tính AB.
b, Gọi M, N lần lượt là trung điểm của OA, OB. Điểm M có nằm giữa hai điểm O và N không? Vì sao? Tính MN.
c, Điểm N có là trung điểm của đoạn thẳng AM không? Vì sao?
cho mìn hỏi câu b nhoa
\(\dfrac{75}{100}\)-\(\dfrac{17}{25}\)+\(\dfrac{13}{37}\)+\(\dfrac{1}{4}\)-\(\dfrac{8}{25}\)+\(\dfrac{24}{37}\)
\(=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(-\dfrac{17}{25}-\dfrac{8}{25}\right)+\left(\dfrac{13}{37}+\dfrac{24}{37}\right)=1\)
Tính.
a)\(N=\dfrac{6:\dfrac{3}{5}-1\dfrac{1}{6}.\dfrac{6}{7}}{\dfrac{1}{5}.\dfrac{10}{11}+5\dfrac{2}{11}}\)
b)Tính nhanh:
\(K=\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{19}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}\)
b, \(K =\) \(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{19}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}\)
\(K = \) \(\dfrac{3}{4}+\dfrac{18}{21}+\dfrac{19}{32}+\dfrac{1}{4}+\dfrac{3}{21}+\dfrac{13}{32}\)
\(K = \) \(\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{18}{21}+\dfrac{3}{21}\right)+\left(\dfrac{19}{32}+\dfrac{13}{32}\right)\)
\(K = \) \(1 + 1 + 1\)
\(K = \) \(3\)
\(S=1\cdot2+2\cdot3+3\cdot4+...+28\cdot29+29\cdot30\)
Tính S