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a; - \(\dfrac{10}{13}\) + \(\dfrac{5}{17}\) - \(\dfrac{3}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{11}{20}\)
= - (\(\dfrac{10}{13}\) + \(\dfrac{3}{13}\)) + (\(\dfrac{5}{17}\) + \(\dfrac{12}{17}\)) - \(\dfrac{11}{20}\)
= - 1 + 1 - \(\dfrac{11}{20}\)
= 0 - \(\dfrac{11}{20}\)
= - \(\dfrac{11}{20}\)
b; \(\dfrac{3}{4}\) + \(\dfrac{-5}{6}\) - \(\dfrac{11}{-12}\)
= \(\dfrac{9}{12}\) - \(\dfrac{10}{12}\) + \(\dfrac{11}{12}\)
= \(\dfrac{10}{12}\)
= \(\dfrac{5}{6}\)
c; [13.\(\dfrac{4}{9}\) + 2.\(\dfrac{1}{9}\)] - 3.\(\dfrac{4}{9}\)
= [\(\dfrac{52}{9}\) + \(\dfrac{2}{9}\)] - \(\dfrac{4}{3}\)
= \(\dfrac{54}{9}\) - \(\dfrac{4}{3}\)
= \(\dfrac{14}{3}\)
1)
a) \(...=4^4-225=256-225=31\)
b) \(...=8.9.5+120=360-120=240\)
c) \(...=3^4-3^3=81-27=54\)
d) \(...=7^2-1=49-1=48\)
2) a) \(...=2^6=64\)
b) \(...=3^{15}:3^{10}=3^5=243\)
c) \(...=3^3-3^3=0\)
d) \(...=6^3+4^5=216+1024=1240\)
a,
A=1−3−5−7−9−...−97−99a)A=1−3−5−7−9−...−97−99
=1−(3+5+7+...+99)=1−(3+5+7+...+99)
=1−(99+3).[(99−3):2+1]2=1−(99+3).[(99−3):2+1]2
=1−2499=−2498=1−2499=−2498
b)B=1+3−5−7+9+...+97−99b)B=1+3−5−7+9+...+97−99
=(−8)+(−8)+(−8)+...+(−8)+97−99=(−8)+(−8)+(−8)+...+(−8)+97−99
=(−8).12+(−2)=−98=(−8).12+(−2)=−98
c)C=1−3−5+7+9−11−13+15+...+97−99c)C=1−3−5+7+9−11−13+15+...+97−99
=0+0+0+0+0+...+0−99=0+0+0+0+0+...+0−99
=−99
Mình không viết lại đề nhé
a) a - 1 - a + 3 = 2
b) 2 +b - b + 1 = 3
c) 4 + a - a + 5 = 9
d) a - 9 - a - 1 = -10
a)(a-1)-(a-3 ).
=a-1-a-3
=(a-a)-(1-3)
=0-(-2)
=2
b) (2+b)-(b-1)
=2+b-b+1
=(2+1)+(b-b)
=3+0
=3
c)(4+a)-(a-5).
=4+a-a+5
=(4+5)+(a-a)
=9+0
=9
d)(a-9)-(a+1)
=a-9-a-1
=(a-a)-(9+1)
=0-10
=-10