Question

tính nhanh

-14/12+0,65-(-7/42-0,35)

(7/8-5/2+4/7)-(-3/7+1-13/8)

Answer 1

\(a,=-\dfrac{14}{12}+\dfrac{13}{20}+\dfrac{7}{42}+\dfrac{7}{20}\\ =\left(\dfrac{13}{20}+\dfrac{7}{20}\right)+\left(-\dfrac{14}{12}+\dfrac{7}{42}\right)\\ =\dfrac{20}{20}-1\\ =1-1=0\\ b,\dfrac{7}{8}-\dfrac{5}{2}+\dfrac{4}{7}+\dfrac{3}{7}-1+\dfrac{13}{8}\\ =\left(\dfrac{4}{7}+\dfrac{3}{7}\right)+\left(\dfrac{7}{8}+\dfrac{13}{8}\right)-\dfrac{5}{2}-1\\ =\dfrac{7}{7}+\dfrac{5}{2}-\dfrac{5}{2}-1\\ =1-1=0\)

Answer 2

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