-7.[(-2)^4+(-36):(-3^2)]-(-5)^3
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15: A= 1/3-3/4+3/5+1/2007-1/36+1/15-2/9
Sửa đề:
A=-3/4-2/9-1/36+1/3+3/5+1/15+1/2007
=-27/36-8/36-1/36+5/15+9/15+1/15+1/2007
=-1+1+1/2007=1/2007
16:
\(A=\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}-\dfrac{3}{4}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{64}\)
\(=\dfrac{5+9+1}{15}+\dfrac{-27-8-1}{36}+\dfrac{1}{64}\)
=1/64
17:
=1/2-1/2+2/3-2/3+3/4-3/4+4/5-4/5+5/6-5/6-6/7
=-6/7
\(a)\dfrac{3}{4}-\dfrac{2}{7}=\dfrac{21-8}{28}=\dfrac{13}{28}.\\ b)\dfrac{3}{8}-\dfrac{5}{16}=\dfrac{6-5}{16}=\dfrac{1}{16}.\)
\(c)\dfrac{7}{5}-\dfrac{2}{3}=\dfrac{21-10}{15}=\dfrac{11}{15}.\\ d)\dfrac{31}{36}-\dfrac{5}{6}=\dfrac{31-30}{36}=\dfrac{1}{36}.\)
\(a,\dfrac{3}{4}-\dfrac{2}{7}=\dfrac{13}{28}\\ b,\dfrac{3}{8}-\dfrac{5}{16}=\dfrac{1}{16}\\ c,\dfrac{7}{5}-\dfrac{2}{3}=\dfrac{11}{15}\\ d,\dfrac{31}{36}-\dfrac{5}{6}=\dfrac{1}{36}\)
\(a,\dfrac{3}{4}-\dfrac{2}{7}=\dfrac{21}{28}-\dfrac{8}{28}=\dfrac{13}{28}\)
\(b,\dfrac{3}{8}-\dfrac{5}{16}=\dfrac{6}{16}-\dfrac{5}{16}=\dfrac{1}{16}\)
\(c,\dfrac{7}{5}-\dfrac{2}{3}=\dfrac{21}{15}-\dfrac{10}{15}=\dfrac{11}{15}\)
\(d,\dfrac{31}{36}-\dfrac{5}{6}=\dfrac{31}{36}-\dfrac{30}{36}=\dfrac{1}{36}\)
Bài 2. > , < , = ?
5/7 < 4/3 2/5 < 6/10 1/4 = 3/12 27/36 >
2/9 7/6 > 7/9
7/2 = 2/7 15/23 < 1 27/9 > 2 14/15 < 1 51/17 < 4
Phương pháp giải:
Nhẩm lại bảng nhân, chia đã học rồi điền kết quả vào chỗ trống.
Lời giải chi tiết:
2 × 3 = 6 4 × 8 = 32
12 : 2 = 6 27 : 3 = 9
4 × 7 = 28 5 × 6 = 30
36 : 4 = 9 18 : 2 = 9
3 × 1 = 3 4 × 3 = 12
0 : 5 = 0 3 × 4 = 12
1 × 8 = 8 12 : 4 = 3
0 : 3 = 0 12 : 3 = 4
Bài 5:
a: =1/3+2/5
=5/15+6/15
=11/15
b: =6/21+12/21=18/21=6/7
c: =16/24+10/24
=26/24
=13/12
d: =4/12+3/12+10/12
=17/12
e: =19/24-9/24
=10/24
=5/12
f: =8/9-3/9=5/9
g: =9/3+1/3=10/3
k: =15/24+42/24+14/24
=71/24
Bạn cần viết đề bằng công thức toán để được hỗ trợ tốt hơn (biểu tượng $\sum$ góc trái khung soạn thảo)
b: \(=\dfrac{2}{5}+\dfrac{3}{5}:\dfrac{9-10}{15}-\dfrac{7}{2}\)
\(=\dfrac{4-35}{10}+\dfrac{3}{5}\cdot\dfrac{15}{-1}\)
\(=\dfrac{-31}{10}-9=\dfrac{-31}{10}-\dfrac{90}{10}=-\dfrac{121}{10}\)
c: \(=\dfrac{48-5}{12}\cdot\dfrac{1}{3}+\dfrac{7}{36}=\dfrac{43}{36}+\dfrac{7}{36}=\dfrac{50}{36}=\dfrac{25}{18}\)
d: \(=\dfrac{17}{6}:\dfrac{6}{5}+\dfrac{-7}{12}\)
\(=\dfrac{85}{36}-\dfrac{7}{12}=\dfrac{85}{36}-\dfrac{21}{36}=\dfrac{64}{36}=\dfrac{16}{9}\)
1: \(\sqrt{3+\sqrt{5}}\cdot\sqrt{2}=\sqrt{6+2\sqrt{5}}=\sqrt{5}+1\)
3) \(\left(\sqrt{\dfrac{3}{4}}-\sqrt{3}+5\cdot\sqrt{\dfrac{4}{3}}\right)\cdot\sqrt{12}\)
\(=\left(\dfrac{\sqrt{3}}{2}-\dfrac{2\sqrt{3}}{2}+5\cdot\dfrac{2}{\sqrt{3}}\right)\cdot\sqrt{12}\)
\(=\dfrac{17\sqrt{3}}{6}\cdot2\sqrt{3}\)
\(=\dfrac{34\cdot3}{6}=\dfrac{102}{6}=17\)
Lời giải:
$-7[(-2)^4+(-36):(-3^2)]-(-5)^3$
$=-7[16+(-36):(-9)]-(-125)$
$=-7(16+4)+125$
$=-7.20+125=-140+125=-15$