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Những câu hỏi liên quan
DT
1
HQ
Hà Quang Minh
Giáo viên
31 tháng 7 2023
\(A=\dfrac{31\cdot\left(31^{12}-1\right)}{31\left(31^{13}+1\right)}=\dfrac{31^{13}+1-32}{31\left(31^{13}+1\right)}=\dfrac{1}{31}-\dfrac{32}{31^{14}+31}\)
\(B=\dfrac{31\left(31^{13}-1\right)}{31\left(31^{14}+1\right)}=\dfrac{1}{31}-\dfrac{32}{31^{15}+31}\)
Dễ thấy \(31^{14}+31< 31^{15}+31\Rightarrow\dfrac{32}{31^{14}+31}>\dfrac{32}{31^{15}+31}\\ \Rightarrow\dfrac{1}{31}-\dfrac{32}{31^{14}+31}< \dfrac{1}{31}-\dfrac{32}{31^{15}+31}\)
Vậy A < B
14 tháng 9 2021
B1:
a) x+2/3=4/5 b) 7/9-x=1/3
x =4/5-2/3 x=7/9-1/3
x =.... x=...
c) x:2/3=9/8
x =9/8.2/3
x =...
H9
HT.Phong (9A5)
CTVHS
24 tháng 8 2023
Bài 2:
a) Các góc kề với góc pOq là:
\(\widehat{sOq};\widehat{nOp};\widehat{mOp}\)
b) Các góc kề bù trong hình là:
\(\widehat{mOn}\) và \(\widehat{sOn}\)
\(\widehat{mOp}\) và \(\widehat{sOp}\)
\(\widehat{mOq}\) và \(\widehat{sOq}\)
18 tháng 8 2023
3:
a: \(\sqrt{14^2}=14\)
b: \(\sqrt{16^2}=16\)
c: \(\sqrt{169}=13\)
d: \(\sqrt{\left(\dfrac{3}{4}\right)^2}=\dfrac{3}{4}\)
1:
a: \(\sqrt{144}=\sqrt{12^2}=12\)
b: \(\sqrt{\left(-13\right)^2}=\left|-13\right|=13\)
c: \(-\sqrt{\dfrac{16}{81}}=-\sqrt{\left(\dfrac{4}{9}\right)^2}=-\dfrac{4}{9}\)
d: \(\sqrt{36}+\sqrt{225}=6+15=21\)
VN
Võ Ngọc Phương
VIP
4 tháng 9 2023
Câu 1:
\(\sqrt{16}=4\)
\(\sqrt{36}=6\)
\(\sqrt{81}=9\)
\(\sqrt{144}=12\)
\(\sqrt{625}=25\)
\(\sqrt{\dfrac{4}{9}}=\dfrac{2}{3}\)
\(\sqrt{\dfrac{36}{25}}=\dfrac{6}{5}\)
\(\sqrt{\dfrac{64}{49}}=\dfrac{8}{7}\)
\(\sqrt{\dfrac{169}{400}}=\dfrac{13}{20}\)
\(\sqrt{11\dfrac{1}{9}}=\sqrt{\dfrac{100}{9}}=\dfrac{10}{3}\)
\(\sqrt{1\dfrac{11}{25}}=\sqrt{\dfrac{36}{25}}=\dfrac{6}{5}\)
\(\sqrt{1\dfrac{13}{36}}=\sqrt{\dfrac{49}{36}}=\dfrac{7}{6}\)
Câu 2:
a) \(3.\sqrt{16}-4\sqrt{\dfrac{1}{4}}\)
\(=3.4-4.\dfrac{1}{2}\)
\(=4.\left(3-\dfrac{1}{2}\right)\)
\(=4.\dfrac{5}{2}\)
\(=10\)
b) \(-5\sqrt{\dfrac{9}{16}}+4\sqrt{0,36}-6\sqrt{0,09}\)
\(=-5.\dfrac{3}{4}+4.0,6-6.0,3\)
\(=\dfrac{-15}{4}+\dfrac{12}{5}-\dfrac{9}{5}\)
\(=\dfrac{-75+48-36}{20}=\dfrac{-63}{20}\)
c) \(2.\sqrt{9}-10.\sqrt{\dfrac{1}{25}}\)
\(=2.3-10.\dfrac{1}{5}\)
\(=6-2\)
\(=4\)
d) \(-3\sqrt{\dfrac{25}{16}}+5\sqrt{0,16}-7\sqrt{0,64}\)
\(=-3.\dfrac{5}{4}+5.0,4-7.0,8\)
\(=\dfrac{-15}{4}+2-\dfrac{28}{5}\)
\(=\dfrac{-75+40-28}{20}=\dfrac{-63}{20}\)
e) \(3\sqrt{25}-27\sqrt{\dfrac{4}{81}}\)
\(=3.5-27.\dfrac{2}{9}\)
\(=15-6\)
\(=9\)
f) \(-21\sqrt{\dfrac{100}{49}}+3\sqrt{0,04}-5\sqrt{0,25}\)
\(=-21.\dfrac{10}{7}+3.0,2-5.0,5\)
\(=-30+\dfrac{3}{5}-\dfrac{5}{2}\)
\(=\dfrac{-300+6-25}{10}=\dfrac{-319}{10}\)
h) \(5\sqrt{9}-4\sqrt{\dfrac{1}{16}}+6\sqrt{25}\)
\(=5.3-4.\dfrac{1}{4}+6.5\)
\(=15-1+30\)
\(=14+30\)
\(=44\)
g) \(10\sqrt{\dfrac{9}{25}}-14\sqrt{\dfrac{36}{49}}+24\sqrt{\dfrac{81}{64}}\)
\(=10.\dfrac{3}{5}-14.\dfrac{6}{7}+24.\dfrac{9}{8}\)
\(=6-12+27\)
\(=\left(-6\right)+27=21\)
Câu 3:
a) \(\sqrt{x}=7\)
\(=>x=49\)
b) \(\sqrt{x}=12\)
\(=>x=144\)
c) \(\sqrt{x}=15\)
\(=>x=225\)
d) \(\sqrt{x}=20\)
\(=>x=400\)
e) \(4\sqrt{x}=8\)
\(\sqrt{x}=8:4\)
\(\sqrt{x}=2\)
\(=>x=4\)
f) \(6\sqrt{x}=3\)
\(\sqrt{x}=\dfrac{3}{6}=\dfrac{1}{2}\)
\(=>x=\dfrac{1}{4}\)
g) \(\sqrt{x-1}=1\)
\(x-1=1\)
\(x=1+1\)
\(=>x=2\)
h) \(\sqrt{x+1}=2\)
\(x+1=4\)
\(x=4-1\)
\(=>x=3\)
i) \(\sqrt{x}-2=7\)
\(\sqrt{x}=7+2\)
\(\sqrt{x}=9\)
\(=>x=81\)
j) \(14-\sqrt{x}=12\)
\(\sqrt{x}=14-12\)
\(\sqrt{x}=2\)
\(=>x=4\)
k) \(12-\sqrt{x-1}=2\)
\(\sqrt{x-1}=12-2\)
\(\sqrt{x-1}=10\)
\(x-1=100\)
\(x=100+1\)
\(=>x=101\)
l) \(\sqrt{x+5}+10=20\)
\(\sqrt{x+5}=20-10\)
\(\sqrt{x+5}=10\)
\(x+5=100\)
\(x=100-5\)
\(=>x=95\)
# Wendy Dang
4 tháng 9 2023
3:
a: ĐKXĐ: x>=0
\(\sqrt{x}=7\)
=>x=7^2=49
b: ĐKXĐ: x>=0
\(\sqrt{x}=12\)
=>x=12^2=144
c: ĐKXĐ: x>=0
\(\sqrt{x}=15\)
=>x=15^2=225
d: ĐKXĐ: x>=0
\(\sqrt{x}=20\)
=>x=20^2=400
e: ĐKXĐ: x>=0
\(4\sqrt{x}=8\)
=>\(\sqrt{x}=2\)
=>x=4
f: ĐKXĐ: x>=0
\(6\cdot\sqrt{x}=3\)
=>\(\sqrt{x}=\dfrac{3}{6}=\dfrac{1}{2}\)
=>x=1/4
g: ĐKXĐ: x>=1
\(\sqrt{x-1}=1\)
=>x-1=1
=>x=2
h: ĐKXĐ: x>=-1
\(\sqrt{x+1}=2\)
=>x+1=4
=>x=3
i: ĐKXĐ: x>=0
\(\sqrt{x}-2=7\)
=>\(\sqrt{x}=9\)
=>x=81
j: ĐKXĐ: x>=0
\(14-\sqrt{x}=12\)
=>\(\sqrt{x}=14-12=2\)
=>x=4
k: ĐKXĐ: x>=1
\(12-\sqrt{x-1}=2\)
=>\(\sqrt{x-1}=10\)
=>x-1=100
=>x=101
i: ĐKXĐ: x>=-5
\(\sqrt{x+5}+10=20\)
=>\(\sqrt{x+5}=10\)
=>x+5=100
=>x=95
TM
1
24 tháng 10 2023
3x-27=4x3 mũ 2
3x-27=4x9
3x-27=36
3x=36+27
3x=63
x=63:3
x=21
DN
1
TH
16 tháng 10 2021
\(a,2\dfrac{1}{3}.5\dfrac{4}{7}=\dfrac{7}{3}.\dfrac{39}{7}=13\)
\(b,\dfrac{-1}{2}+\dfrac{4}{9}+\dfrac{3}{2}+\dfrac{5}{9}=-1+1=0\)
\(c,0,75+\left(-1,25\right)=-1,50\)
\(d,\dfrac{2}{5}\cdot\dfrac{3}{8}-\dfrac{2}{5}\cdot\dfrac{6}{11}=\dfrac{2}{5}\cdot\left(\dfrac{3}{8}-\dfrac{6}{11}\right)=\dfrac{2}{5}.\dfrac{-15}{88}=\dfrac{-3}{44}\)
S
16 tháng 1 2022
PTHH : 2Al + 6HCl --> 2AlCl3 + 3H2 ↑ (1)
nAlCl3 = \(\dfrac{m}{M}=\dfrac{13,35}{27+35,5.3}=0.1\left(mol\right)\)
Từ (1) => nHCl = 2nH2 = 0.2 (mol)
=> mHCl = n.M = 0.2 x 36.5 = 7.3 (g)
16 tháng 1 2022
\(PTHH:2Al+6HCl\rightarrow2AlCl_3+3H_2\\ n_{AlCl_3}=\dfrac{m}{M}=\dfrac{13,35}{133,5}=0,1\left(mol\right)\\ Theo.PTHH:n_{HCl}=3.n_{AlCl_3}=3.0,1=0,3\left(mol\right)\\ m_{HCl}=n.M=0,3.36,5=10,95\left(g\right)\)
DT
Đỗ Thanh Hải
CTVVIP
19 tháng 7 2021
10 to persuade
1 seasonality
2 facilitators
3 inexperienced
4 recruitments
5 weighless
Bài 1:
a. (72306 : 351 + 5794) - 142 x 37
= (206 + 5794) - 142 x 37
= 6000 - 142 x 37
= 6000 - 5254
= 746
b.\(5\times\frac{2}{7}:\frac{5}{35}-\frac{3}{4}\)
\(=\frac{10}{7}.\frac{1}{7}-\frac{3}{4}\)
\(=\frac{10}{49}-\frac{3}{4}\)
\(=\frac{40}{196}-\frac{147}{196}\)
\(=\frac{40}{196}+\frac{-147}{196}\)
\(=\frac{-107}{196}\)
~HT~
thanks