Bài 1: Tính hợp lý:
a. 1152 - (374 + 1152) + (374 - 65)
b. dfrac{7}{12} + dfrac{5}{6} + dfrac{1}{4} - dfrac{3}{7} - dfrac{5}{12}
c. dfrac{11.3^{22}.3^7-9^{15}}{left(2.3^{14}right)^2}
d, dfrac{3}{2^2} . dfrac{8}{3^2} . dfrac{15}{4^2} ... dfrac{899}{30^2}
Bài 2: Tìm x biết:
a, 2x + 2x+1 + 2x+2 + 2 x+3 480
b, left(dfrac{1}{2}+dfrac{1}{3}+...+dfrac{1}{2012}+dfrac{1}{2013}right) . x dfrac{2012}{1}+dfrac{2011}{2}+dfrac{2010}{3}+...+dfrac{2}{2011}+dfrac{1}{2012}.
Đọc tiếp
Bài 1: Tính hợp lý:
a. 1152 - (374 + 1152) + (374 - 65)
b. \(\dfrac{7}{12}\) + \(\dfrac{5}{6}\) + \(\dfrac{1}{4}\) - \(\dfrac{3}{7}\) - \(\dfrac{5}{12}\)
c. \(\dfrac{11.3^{22}.3^7-9^{15}}{\left(2.3^{14}\right)^2}\)
d, \(\dfrac{3}{2^2}\) . \(\dfrac{8}{3^2}\) . \(\dfrac{15}{4^2}\) ... \(\dfrac{899}{30^2}\)
Bài 2: Tìm x biết:
a, 2x + 2x+1 + 2x+2 + 2 x+3 = 480
b, \(\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2012}+\dfrac{1}{2013}\right)\) . x = \(\dfrac{2012}{1}+\dfrac{2011}{2}+\dfrac{2010}{3}+...+\dfrac{2}{2011}+\dfrac{1}{2012}.\)
13