(12/7x6+1254:1/4)x(12/6x2015+99x2015-2015x101)
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\(a,4^8.2^{20}=\left(2^2\right)^8.2^{20}=2^{16}.2^{20}=2^{16+20}=2^{36}\\ b,9^{12}.27^5.81^4=\left(3^2\right)^{12}.\left(3^3\right)^5.\left(3^4\right)^4=3^{24}.3^{15}.3^{16}=3^{24+15+16}=3^{55}\\ d,25^{20}.125^4=\left(5^2\right)^{20}.\left(5^3\right)^4=5^{40}.5^{12}=5^{40+12}=5^{52}\\ d,x^7.x^4.x^3=x^{7+4+3}=x^{14}\)
a: 4*8*2^20=2^2*2^3*2^20=2^25
b: 9^12*27^5*81^4=3^24*3^15*3^16=3^55
c: 25^20*125^4=5^40*5^12=5^52
d: =x^(7+4+3)=x^14
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Bài 1: Tính hợp lí:
a) (-81 -124) -(76 -81)
= -81 -124 - 76 +81
= (-81 + 81) - (124 + 76)
= 0 - 200 = -200
b) 1009 - (1009 +111) -89
= 1009 - 1009 - 111 -89
= (1009 - 1009) - ( 111 +89)
= 0 - 200 = -200
c) (-247 +63) -(63 - 247)
= -247 + 63 -63 + 247
= (-247 +247) + (63-63)
= 0+0 =0
d) 1254 - (459 - 1254) - 541
= 1254 - 459 + 1254 - 541
= (1254+1254) - (459 + 541)
= 2508 - 1000 = 1508
Bài 2: Tìm x
a)x - 148 - 2x - 150
(x-2x) - (148 + 150) = ?
-1x - 298 = ?
-1x = ? + 298
.... Từ đó tự giải tiếp
b)15 - (10-2x)-x-29
15 - 10 + 2x -x - 29 =?
(15-10-29) + (2x -x) =?
(-24) + x =?
x = ? + 24
... Từ đó tự giải tiếp
c) ( -2x + 12) -(3x -14)= (6x +1)+ (-12x -17)
-2x + 12 - 3x + 14 = 6x + 1 - 12x - 17
(-2x - 3x) + ( 12 + 14) = (6x - 12x) + (1-17)
(-5x) + 26= (-6x) + (-16)
(-5x) + 6x = (-16) - 26
x = -42
Chúc bạn học tốt ! ^^ ~~~
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a)\(16^6:4^2=\left(4^2\right)^6:4^2=4^{12-2}=4^{10}\)
b)\(18^8:9^4=\left(2.9\right)^8:9^4=2^8.9^8:9^4=2^8.9^4=\left(2^2.9\right)^4=36^4\)
c)\(125^4:25^3=\left(5^3\right)^4:\left(5^2\right)^3=5^{12}:5^6=5^6\)
d)\(12^n:2^{2n}=\left(2^2.3\right)^n:2^{2n}=2^{2n}.3^n:2^{2n}=3^n\left(n\inℕ^∗\right)\)
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1)
`x^2 -144=0`
`<=> x^2 =144`
\(< =>\left[{}\begin{matrix}x=12\\x=-12\end{matrix}\right.\)
2)`
`2x^2 -72=0`
`<=>2x^2 =72`
`<=>x^2=36`
\(< =>\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)
3)
`5x^2 -125=0`
`<=> 5x^2 =125`
`<=>x^2 =25`
\(< =>\left[{}\begin{matrix}x=5\\x=-5\end{matrix}\right.\)
4)
`-x^2 +81=0`
`<=> x^2 -81=0`
`<=> x^2 =81`
\(< =>\left[{}\begin{matrix}x=9\\x=-9\end{matrix}\right.\)
5)
`x(2x-18)=0`
\(< =>\left[{}\begin{matrix}x=0\\2x-18=0\end{matrix}\right.\\ < =>\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)
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b) \(-2x+\left(-3x\right)+\left(-4x\right)+......+\left(-20x\right)=1254\)
\(\Rightarrow x.\left(-2-3-4-.......-20\right)=1254\)
\(\Rightarrow x.\left[-\left(2+3+4+.....+20\right)\right]=1254\)
\(\Rightarrow x.\left(-209\right)=1254\)
\(\Rightarrow x=1254:\left(-209\right)\)
\(\Rightarrow x=-6\)
c) \(\left|2x\right|=4\)
\(\Rightarrow\orbr{\begin{cases}2x=4\\2x=-4\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)
d) \(\left|2x-1\right|=3\)
\(\Rightarrow\orbr{\begin{cases}2x-1=3\\2x-1=-3\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}2x=4\\2x=-2\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=2\\x=-1\end{cases}}\)
=A*(2*2015+99*2015-101*2015)
=2015*A*(2+99-101)=0