Question

[AI AI]

Tính một cách hợp lí

a. \(8\dfrac{5}{7}+3,15+1\dfrac{2}{7}+4,35\)

b. \(\left(4\dfrac{5}{23}-2\dfrac{2}{5}+7\dfrac{7}{13}\right)-\left(3\dfrac{5}{23}-6\dfrac{6}{13}\right)\)

c. \(-15\dfrac{1}{2}\times20,8+3,5\times9,5-15,5\times9,2+3\dfrac{1}{2}\times20\dfrac{1}{2}\)

giúp mk với , mai mk phải nộp bài rồi
cảm ơn các bn trước nha

Answer 1

[Cô Bé Họ Tạ]

a. $8\frac{5}{7}+3,15+1\frac{2}{7}+4,35$

$\mathrm{=\backslash (\backslash dfrac\{61\}\{7\}+\backslash dfrac\{63\}\{20\}+\backslash dfrac\{9\}\{7\}+\backslash dfrac\{87\}\{20\}\backslash )}$

=\(\left(\dfrac{61}{7}+\dfrac{9}{7}\right)+\left(\dfrac{63}{20}+\dfrac{87}{20}\right)\)

=\(10+\dfrac{15}{2}\)

=\(\dfrac{35}{2}\)

b. $\left(4\frac{5}{23}-2\frac{2}{5}+7\frac{7}{13}\right)-\left(3\frac{5}{23}-6\frac{6}{13}\right)$

$=\backslash (4\backslash dfrac\{5\}\{23\}-2\backslash dfrac\{2\}\{5\}+7\backslash dfrac\{7\}\{13\}-3\backslash dfrac\{5\}\{23\}+6\backslash dfrac\{6\}\{13\}\backslash )$

=\(\left(4\dfrac{5}{23}-3\dfrac{5}{23}\right)+\left(7\dfrac{7}{13}+6\dfrac{6}{13}\right)-2\dfrac{2}{5}\)

=\(1+14-\dfrac{12}{5}\)

=15-\(\dfrac{12}{5}\)

=\(\dfrac{63}{5}\)

Câu C khó khó mình chưa giải được !!!