Help:((
3 mũ4*5 mũ4-(15mũ2+1)(15mũ2 -1)
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\(\left(-0,25\right)^4\cdot4^4\)
\(=\left(-\dfrac{1}{4}\right)^4\cdot4^4\)
\(=\left(-\dfrac{1}{4}\cdot4\right)^4\)
\(=\left(-\dfrac{4}{4}\right)^4\)
\(=\left(-1\right)^4\)
\(=1\)
a)(1000+1):11
=1001:11
=91
91=7.13
b)142+52+22
=196+25+4
=221+4
=225
225=32.52
c)333:3+225:152
=333:3+225:225
=111+1
=112
112=24.7
tớ làm đầy đủ li-ke cho tớ nha
(5x-24).73=2.74
5x-16=2.(74:73)
5x-16=2.7
5x-16=14
5x=14+16
5x=30
x=30:5=6
S = 1 + 2 + 22 + 23 + 24 + 25 + 26 + 27
= (1 + 2) + (22 + 23) + (24 + 25) + (26 + 27)
= (1 + 2) + 22(1 + 2) + 24(1 + 2) + 26(1 + 2)
= (1 + 2)(1 + 22 + 24 + 26)
= 3(1 + 22 + 24 + 26) \(⋮3\)(ĐPCM)
2S = 1 + 2 + 22 + 23 + 24 + 25 + 26 + 27
S = (1+2 ) + (22 + 23 ) + (24 + 25 ) + (26 +27)
S = 3 + 22(1+2) + 24(1+2) + 26(1+2)
S = 3+22.3 + 24.3 + 26 .3
S = 3(1+22 + 24 + 26 ) \(⋮\) 3
=> đpcm
A=1+3+3^2+3^3+3^4+3^5+3^6
3A=3+3^2+3^3+3^4+3^5+3^6+3^7
3A-A=(3+3^2+3^3+3^4+3^5+3^6+3^7)-(1+3+3^2+3^3+3^4+3^5+3^6)
A=3^7-1
Vì A =3^7-1 ; B =3^7-1
=> A=B
Sửa đề:
\(A=1+3+3^2+3^3+3^4+3^5+3^6\)
\(3A=3+3^2+...+3^7\)
\(3A-A=\left(3+3^2+3^3+...+3^7\right)-\left(1+3+3^2+...+3^6\right)\)
\(2A=3^7-1\)
\(\Rightarrow A=\frac{3^7-1}{2}< 3^7-1=B\)
Vậy \(A< B\)
\(3^4.5^4-\left(15^2+1\right)\left(15^2-1\right)\)
\(=\left(3.5\right)^4-\left[\left(15^2\right)^2-1\right]\)
\(=15^4-\left(15^4-1\right)=15^4-15^4+1=1\)