thu gọn các biểu thức sau:
a)4^10 . 8^15
b)4^15 . 5^30
c)27^16 : 9^10
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A) 410 . 815 = (22)10 . (23)15 = 220 . 245 = 220+45=265
B) 415 . 530 = (22)15 . 530 = 230 . 530 = (2 . 5)30 = 1030
C) 2716 : 910 = (33)16 : (32)10 = 348 : 320 = 348-20=328
a: =căn 3+căn 5-căn 3=căn5
b: \(=\sqrt{x-2-2\sqrt{x-2}+1}=\sqrt{\left(\sqrt{x-2}-1\right)^2}\)
\(=\left|\sqrt{x-2}-1\right|\)
1: Ta có: \(P=\dfrac{x-\sqrt{x}}{x-9}+\dfrac{1}{\sqrt{x}+3}-\dfrac{1}{\sqrt{x}-3}\)
\(=\dfrac{x-\sqrt{x}+\sqrt{x}-3-\sqrt{x}-3}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-3\right)}\)
\(=\dfrac{x-\sqrt{x}-6}{\left(\sqrt{x}+3\right)\left(\sqrt{x}-3\right)}\)
\(=\dfrac{\left(\sqrt{x}-3\right)\left(\sqrt{x}+2\right)}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}\)
\(=\dfrac{\sqrt{x}+2}{\sqrt{x}+3}\)
2)
a) Thay \(x=\dfrac{9}{4}\) vào P, ta được:
\(P=\left(\dfrac{3}{2}+2\right):\left(\dfrac{3}{2}+3\right)=\dfrac{7}{2}:\dfrac{11}{2}=\dfrac{7}{11}\)
b) Ta có: \(x=\sqrt{27+10\sqrt{2}}-\sqrt{18+8\sqrt{2}}\)
\(=5+\sqrt{2}-4-\sqrt{2}\)
=1
Thay x=1 vào P, ta được:
\(P=\dfrac{1+2}{1+3}=\dfrac{3}{4}\)
a) 53.252:54
= 53.(52)2:54
= 53.54:54
= 53+4-4
= 53
b) 42.(23)2:128
= (22)2.26:27
= 24.26:27
= 24+6-7
= 23
c) 35.243:(32)3
= 35.35:36
= 35+5-6
= 34
d) 205:55
= (20:5)5
= 45
e) 410:810 (Có chắc không vậy ? Hay là 810:410 ?)
g) 415.530
= 415.(52)15
= 415.2515
= (4.25)15
= 10015
h) 2716.910
= (33)16.(32)10
= 348.320
= 348+20
= 368
a: 15 mod 2=1
b: 27 div 5=5
c: 17 mod 3=2
d: 21 div 2=10
e: 10 mod 4=2
f: 23 div 5=4
`c)root{3}{4}.root{3}{1-sqrt3}.root{6}{(sqrt3+1)^2}`
`=root{3}{4(1-sqrt3)}.root{3}{1+sqrt3}`
`=root{3}{4(1-sqrt3)(1+sqrt3)}`
`=root{3}{4(1-3)}=-2`
`d)2/(root{3}{3}-1)-4/(root{9}-root{3}{3}+1)`
`=(2(root{3}{9}+root{3}{3}+1))/(3-1)-(4(root{3}{3}+1))/(3+1)`
`=root{3}{9}+root{3}{3}+1-root{3}{3}-1`
`=root{3}{9}`
`a)root{3}{8sqrt5-16}.root{3}{8sqrt5+16}`
`=root{3}{(8sqrt5-16)(8sqrt5+16)}`
`=root{3}{320-256}`
`=root{3}{64}=4`
`b)root{3}{7-5sqrt2}-root{6}{8}`
`=root{3}{1-3.sqrt{2}+3.2.1-2sqrt2}-root{6}{(2)^3}`
`=root{3}{(1-sqrt2)^3}-sqrt2`
`=1-sqrt2-sqrt2=1-2sqrt2`