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Bài 8:
a: \(\left(\dfrac{2}{5}+\dfrac{3}{4}\right)^2=\left(\dfrac{8+15}{20}\right)^2=\left(\dfrac{23}{20}\right)^2=\dfrac{529}{400}\)
b: \(\left(\dfrac{5}{4}-\dfrac{1}{6}\right)^2=\left(\dfrac{15}{12}-\dfrac{2}{12}\right)^2=\left(\dfrac{13}{12}\right)^2=\dfrac{169}{144}\)
\(a,\left(\frac{3}{8}+-\frac{3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
= \(\left(-\frac{3}{8}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
= \(\frac{5}{24}:\frac{5}{6}+\frac{1}{2}\)
= \(\frac{1}{4}+\frac{1}{2}\)
= \(\frac{3}{4}\)
b)\(-\frac{7}{3}.\frac{5}{9}+\frac{4}{9}.\left(-\frac{3}{7}\right)+\frac{17}{7}\)
=\(-\frac{35}{27}+\left(-\frac{4}{21}\right)+\frac{17}{7}\)
= \(-\frac{35}{27}+\frac{47}{21}\)
= \(\frac{178}{189}\)
c) \(\frac{117}{13}-\left(\frac{2}{5}+\frac{57}{13}\right)\)
= \(\frac{117}{13}-\frac{311}{65}\)
= \(\frac{274}{65}\)
d) \(\frac{2}{3}-0,25:\frac{3}{4}+\frac{5}{8}.4\)
= \(\frac{2}{3}-\frac{1}{4}:\frac{3}{4}+\frac{5}{8}.4\)
= \(\frac{2}{3}-\frac{1}{3}+\frac{5}{2}\)
= \(\frac{1}{3}+\frac{5}{2}\)
= \(\frac{17}{6}\)
2, 100^2+200^2+300^2+..+1000^2
=100^2+2^2×100^2+3^2×100^2+...+100^2×10^2
=100^2×( 1^2+2^2+3^2+..+10^2)
=100^2×385
= 3850000
BẠN RẢNH QUÁ!!!
VIẾT CẢ MỘT TRANG DÀI NHƯ BẠN CHẮC HỔNG CÓ THỜI GIAN.
KẾT BẠN VỚI TUI ĐI!!!
Bài 1
a) x:(3/4)3=(3/4)2=>x=(3/4)2.(3/4)3=(3/4)2+3=(3/4)5
b) (2/5)5.x=(2/5)8=>x=(2/5)8:(2/5)5=(2/5)8-5=(2/5)3
Bài 2
(0,36)8=[ (0,6)2 ]8=(0,6)2.8=(0,6)16
(0,216)4=[ (0,6)3 ]4=(0,6)3.4=(0,6)12
Bài 3
a) (1/3)m=1/81=(1/3)4 => m=4
b) (3/5)n=(9/25)5=[ (3/5)2 ]5=(3/5)2.5=(3/5)10=>n=10
c) (-0,25)p=1/256=(1/4)4=(0,25)4=(-0,25)4=>p=4
bai3
a (1/3)^m=(1/3)^4 =>m=4
b) n=10 (làm tuong tu cau a)
c ) p=4 (doi -0.25=-1/4)
cau 2(0.36)^8=0.6)^16
(0.216)^4=0.6)12