\(\frac{7}{15}+0.3-\frac{4}{17}+\frac{8}{15}-\frac{13}{17}\)
tính bằng cách hợp lí
Bài 12 : Thực hiện phép tính một cách hợp lí:
p) \(\frac{-5}{9}+\frac{8}{15}+\frac{-2}{11}+\frac{4}{-9}+\frac{7}{15}\) q) \(\frac{5}{13}+\frac{-5}{17}+\frac{-20}{41}+\frac{8}{13}+\frac{-21}{41}\) r) \(\frac{1}{5}+\frac{-2}{9}+\frac{-7}{9}+\frac{4}{5}+\frac{16}{17}\)
p) \(\frac{-5}{9}+\frac{8}{15}+\frac{-2}{11}+\frac{4}{-9}+\frac{7}{15}\)
\(=\left(\frac{-5}{9}+\frac{-4}{9}\right)+\left(\frac{8}{15}+\frac{7}{15}\right)+\frac{-2}{11}\)
\(=-1+1+\frac{-2}{11}\)
\(=-\frac{2}{11}\)
q) \(\frac{5}{13}+\frac{-5}{17}+\frac{-20}{41}+\frac{8}{13}+\frac{-21}{41}\)
\(=\left(\frac{5}{13}+\frac{8}{13}\right)+\left(\frac{-20}{41}+\frac{-21}{41}\right)+\frac{-5}{17}\)
\(=1+\left(-1\right)+\frac{-5}{17}=\frac{-5}{17}\)
r) \(\frac{1}{5}+\frac{-2}{9}+\frac{-7}{9}+\frac{4}{5}+\frac{16}{17}\)
\(=\left(\frac{1}{5}+\frac{4}{5}\right)+\left(\frac{-2}{9}+\frac{-7}{9}\right)+\frac{16}{17}\)
\(=1+\left(-1\right)+\frac{16}{17}=\frac{16}{17}\)
Tính hợp lí: \(\frac{12}{9}.\frac{7}{15}.\frac{-13}{17}.\frac{19}{12}.\frac{17}{13}\)
Câu 1: Thực hiện phép tính bằng cách hợp lí
\(\frac{15}{35}+\frac{7}{21}+\frac{19}{34}-1\frac{15}{17}+\frac{2}{3}\)
\(\left(-2\right)^3.\left(\frac{3}{4}-0,25\right):\left(2\frac{1}{4}-1\frac{1}{6}\right)\)
\(16\frac{2}{7}:\left(-\frac{3}{5}\right)+28\frac{2}{7}:\left(-\frac{3}{5}\right)\)
Câu 2: Tìm x biết
\(2.x-\frac{5}{4}=\frac{20}{15}\)
\(1,5:0,3=x:-15\)
\(|2x-1|=2\)
Câu 3: Thực hiện phép tính hợp lí
\(\frac{11}{12}.\frac{15}{33}+\frac{11}{12}.\frac{2}{22}\)
\(3/3\frac{1}{8}.11\frac{17}{19}-3\frac{1}{8}.13\frac{17}{19}\)
\(28\frac{2}{7}:\left(-\frac{3}{5}\right)+16\frac{2}{7}:\left(-\frac{3}{5}\right)\)
Tính nhanh:
\(\frac{4}{17}-\frac{7}{15}+\frac{13}{17}-\frac{8}{15}+\frac{5}{8}-\frac{7}{16}\)
\(=\left(\frac{4}{17}+\frac{13}{17}\right)-\left(\frac{7}{15}+\frac{8}{15}\right)+\left(\frac{10}{16}-\frac{7}{16}\right)\)
\(=1-1+\frac{3}{16}\)
\(\frac{3}{16}\)
gộp 1,3
2,4
5,6
thì ra 17/17-15/15+3/16=3/16
hk tốt!
Tính một cách hợp lí:
M= \(\frac{75+\frac{6}{13}+\frac{3}{17}+\frac{3}{19}}{100+\frac{8}{13}+\frac{4}{17}+\frac{4}{19}}\)
Tính bằng cách hợp lí
a)\(\frac{1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}}{1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}}:\frac{13+\frac{13}{2}+\frac{13}{3}+\frac{13}{4}}{17-\frac{17}{2}+\frac{17}{3}-\frac{17}{4}}\)
Tính một cách hợp lí:
a) A = \(\frac{9}{11}+\frac{5}{7}-\frac{20}{11}+\frac{8}{13}+\frac{2}{7}\) b) \(B=\frac{8}{13}+\frac{9}{-17}+\frac{-34}{13}+\frac{-8}{17}\)
\(\text{a)}A=\frac{9}{11}+\frac{5}{7}-\frac{20}{11}+\frac{8}{13}+\frac{2}{7}\)
\(A=\frac{9}{11}+\frac{5}{7}+\frac{-20}{11}+\frac{8}{13}+\frac{2}{7}\)
\(A=\left(\frac{9}{11}+\frac{-20}{11}\right)+\left(\frac{5}{7}+\frac{2}{7}\right)+\frac{8}{13}\)
\(A=\frac{-11}{11}+\frac{7}{7}+\frac{8}{13}\)
\(A=\left[\left(-1\right)+1\right]+\frac{8}{13}\)
\(A=0+\frac{8}{13}=\frac{8}{13}\)
\(\text{b)}B=\frac{8}{13}+\frac{9}{-17}+\frac{-34}{13}+\frac{-8}{17}\)
\(B=\left(\frac{8}{13}+\frac{-34}{13}\right)+\left(\frac{-9}{17}+\frac{-8}{17}\right)\)
\(B=\frac{-26}{13}+\left(-1\right)\)
\(B=\left(-2\right)+\left(-1\right)=-3\)
\(\text{Hok tốt!}\)
\(\text{@Kaito Kid}\)
Tính
A= \(\frac{50-\frac{4}{13}+\frac{2}{15}-\frac{2}{17}}{100-\frac{8}{13}+\frac{4}{15}-\frac{4}{17}}\)
\(=\frac{50-\frac{4}{13}+\frac{2}{15}-\frac{2}{17}}{2\left(50-\frac{4}{13}+\frac{2}{15}-\frac{2}{17}\right)}=\frac{1}{2}\)
Bài 1: Thực hiện các phép tính dau bằng cách hợp lí
a. \(\frac{11}{225}-\frac{17}{18}-\frac{5}{7}+\frac{4}{9}+\frac{17}{14}\)
b. \(1-\frac{1}{2}+2-\frac{2}{3}+3-\frac{3}{4}+4-\frac{1}{4}-3-\frac{1}{3}-2-\frac{1}{2}-1\)
Bài 2: Tìm x biết
a. \(\frac{11}{13}-\left(\frac{5}{42}-x\right)=-\left(\frac{15}{28}-\frac{11}{13}\right)\)
b. \(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
Bài 3: Thực hiện các phép tính sau bằng cách hợp lí nhất
a. \(\left(-\frac{40}{51}\cdot0,32\cdot\frac{17}{20}\right):\frac{64}{75}\)
b. \(-\frac{10}{11}\cdot\frac{8}{9}+\frac{7}{18}\cdot\frac{10}{11}\)
c. \(\frac{3}{14}:\frac{1}{28}-\frac{13}{21}:\frac{1}{28}+\frac{29}{42}-8\)
d. \(-1\frac{5}{7}\cdot15+\frac{2}{7}.\left(-15\right)+\left(-105\right).\left(\frac{2}{3}-\frac{4}{5}+\frac{1}{7}\right)\)
Bìa 4: Tính giá trị của các biểu thức sau
a. \(A=7x-2x-\frac{2}{3}y+\frac{7}{9}y\) với \(x=-\frac{1}{10};y=4,8\)
b. \(B=x+\frac{0,2-0,375+\frac{5}{11}}{-0,3+\frac{9}{16}-\frac{15}{22}}\) với\(x=-\frac{1}{3}\)