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a) = -120
b) = 3 x (-4)
= -12
c) = -8 x 2
= -16
d) = -18 : (-6)
= 3
a) (-4) . (-5) . (-6)
= 20 . (-6)
= (-120)
b) (-3 + 6) . (-4)
= (-3) . (-4)
= 12
c) (-3 -5) . (-3+5)
= (-8) . 2
=(-16)
d) (-5 -13) : (-6)
= (-18) : (-6)
= 3
Mình làm mẫu 1 bài rùi bạn tự giải những bài còn lại nha
1, 7A = 7+7^2+7^3+....+7^2008
6A = 7A - A = (7+7^2+7^3+....+7^2008)-(1+7+7^2+....+7^2007) = 7^2008-1
=> A = (7^2008-1)/6
Tk mk nha
\(A=1+7+7^2+7^3+...+7^{2007}\)
\(\Rightarrow7A=7+7^2+7^3+7^4+...+7^{2008}\)
\(\Rightarrow7A-A=\left(7+7^2+7^3+...+7^{2008}\right)-\left(1+7+7^2+...+7^{2007}\right)\)
\(\Rightarrow6A=7^{2008}-1\)
\(\Rightarrow A=\frac{7^{2008}-1}{6}\)
a)\(\dfrac{-6}{11}:\left(\dfrac{3}{5}.\dfrac{4}{11}\right)=\dfrac{-5}{2}\)
b)\(\dfrac{7}{12}+\dfrac{5}{12}:6-\dfrac{14}{30}=\dfrac{67}{370}\)
c)\(\left(\dfrac{4}{5}+\dfrac{1}{2}\right):\left(\dfrac{3}{13}-\dfrac{8}{13}\right)=-\dfrac{169}{50}\)
d)\(\left(\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}\right):\left(\dfrac{5}{12}+1-\dfrac{7}{11}\right)=\dfrac{115}{103}\)
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.\(\dfrac{4}{9}\)
= [\(\dfrac{52}{9}\) + \(\dfrac{2}{9}\)] - \(\dfrac{4}{3}\)
= \(\dfrac{54}{9}\) - \(\dfrac{4}{3}\)
= \(\dfrac{14}{3}\)
mình viết đáp án luôn nhé
a,x=845/528
b,-7/5
c,-47/140
d,43/1710
chúc bạn làm bài thành công nhe!!@
các bạn nhớ chọn k đúng cho mình nhé
a) (–4) . (–5) . (–6) = [(- 4).(- 5)].(- 6) = 20.(- 6) = -(20.6) = -120
b) (–3 + 6) . (–4) = 3 . (–4) = – (3 . 4) = –12
c) (–3 –5) . (–3 + 5) = (–8) .2 = –(8 . 2) = –16;
d) (–5 – 13) : (–6) = (–18) : (–6) = 18 : 6 = 3.
a) \(\left(-4\right).\left(-5\right).\left(-6\right)=20.\left(-6\right)=\left(-120\right)\)
b) \(\left(-3+6\right).\left(-4\right)=3.\left(-4\right)=-12\)
c) \(\left(-3-5\right).\left(-3+5\right)=\left(-8\right).2=\left(-16\right)\)
d) \(\left(-5-13\right):\left(-6\right)=\left(-18\right):\left(-6\right)=3\)