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-72(15-49) + 15 (-56 + 72)
= -72 . -34 + 15 . 16
= 2488 + 240
= 2728
-72(15-49)+15(-56+72) =-72.(-34)+15.16 =2448+240 = 2688 làm luôn :16.17.1.15625.1 =272.15625 =4250000
A=\(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}...\frac{2014}{2015}.\frac{2015}{2016}\)
A=\(\frac{1.2.3.4...2015}{2.3.4...2016}=\frac{1}{2016}\)
Hok tốt
A = \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{2015}\right).\left(1-\frac{1}{2016}\right)\)
= \(\frac{1}{2}.\frac{2}{3}.\frac{3}{4}...\frac{2014}{2015}.\frac{2015}{2016}\)
= \(\frac{1}{2016}\)
Vậy ...
\(\hept{\begin{cases}3^2.\left(-2\right)^3=9.-8=-72\\-58\end{cases}}\) =>\(-72< -58=>3^2.\left(-2\right)^3< -58\)
\(\hept{\begin{cases}\left(-4\right)^3=-64\\\left|-6^2\right|=36\end{cases}=>-64< 36}=>\left(-4\right)^3< \left|-6^2\right|\)
\(3^2.\left(-2\right)^3=9.\left(-8\right)=\left(-72\right)\)
Vì (-72)<(-58) nên 32.(-2)3<(-58)
Có (-4)3 có gt âm
\(|-6^2|\)có gt dương
mà âm luôn luôn < dương
nên (-4)3<\(|-6^2|\)
\(\Leftrightarrow\left(2x-15\right)^5-\left(2x-15\right)^3=0\)
\(\Leftrightarrow\hept{\begin{cases}\left(2x-15\right)^5=0\\\left(2x-15\right)^3=0\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}2x-15=0\\2x-15=0\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}2x=15\\2x=15\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x=\frac{15}{2}\\x=\frac{15}{2}\end{cases}}\)
vậy...
Bài giải
a, Ta có : \(\frac{2x+5}{x+2}=\frac{2\left(x+2\right)+1}{x+2}=\frac{2\left(x+2\right)}{x+2}+\frac{1}{x+2}=2+\frac{1}{x+2}\)
\(2x+5\text{ }⋮\text{ }x+2\text{ khi }1\text{ }⋮\text{ }x+2\text{ }\Rightarrow\text{ }x+2\inƯ\left(1\right)\)
\(\Rightarrow\orbr{\begin{cases}x+2=-1\\x+2=1\end{cases}}\Rightarrow\orbr{\begin{cases}x=-3\\x=-1\end{cases}}\)
\(\Rightarrow\text{ }x\in\left\{-3\text{ ; }-1\right\}\)
a) \(2\left(x+2\right)+1⋮x+2\)
\(\Leftrightarrow1⋮x+2\)
b) \(3x+5⋮x-2\)
\(\Leftrightarrow3\left(x-2\right)+11⋮x-2\)
\(\Leftrightarrow11⋮x-2\)
c) \(x^2+3⋮x+4\)
\(\Leftrightarrow\left(x^2-16\right)+19⋮x+4\)
\(\Leftrightarrow\left(x-4\right)\left(x+4\right)+19⋮x+4\)
\(\Leftrightarrow19⋮x+4\)
P/s : Mình chỉ làm đến bước này thôi, các bước tiếp theo bạn tự làm nhé. Chúc bạn học tốt !
a) ( -32 ) . ( -56 ) + 32.44
= 32 . 56 + 32 . 44
= 32 . ( 56 + 44 )
= 32 . 100
= 3200
b) Làm tương tự như phần a nhé !
Kết bạn nhé !
a) \(\left(-32\right)\cdot\left(-56\right)+32\cdot44\)
\(=32\cdot56+32\cdot44\)
\(=32\cdot\left(56+44\right)\)
\(=32\cdot100\)
\(=3200\)
b) \(\left(-59\right)\cdot\left(-56\right)-59\cdot53\)
\(=59\cdot56-59\cdot53\)
\(=59\cdot\left(56-53\right)\)
\(=59\cdot3\)
\(=177\)
Bài 1:
a) b) c) sẽ có bạn giải cho em thôi vì nó dễ tính tay cũng đc
d) \(\frac{4}{2.5}+\frac{4}{5.8}+...+\frac{4}{23.26}\)
\(=\frac{4}{3}.\left(\frac{3}{2.5}+\frac{3}{5.8}+...+\frac{3}{23.26}\right)\)
\(=\frac{4}{3}.\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{23}-\frac{1}{26}\right)\)
\(=\frac{4}{3}.\left(\frac{1}{2}-\frac{1}{26}\right)\)
\(=\frac{4}{3}.\frac{6}{13}\)
\(=\frac{8}{13}\)
Bài 2:
a) b) c)
d)\(|\frac{5}{8}x+\frac{6}{7}|-\frac{4}{7}=\frac{10}{7}\)
\(\Leftrightarrow|\frac{5}{8}x+\frac{6}{7}|=2\)
\(\Leftrightarrow\orbr{\begin{cases}\frac{5}{8}x+\frac{6}{7}=2\\\frac{5}{8}x+\frac{6}{7}=-2\end{cases}}\)\(\Leftrightarrow\orbr{\begin{cases}\frac{5}{8}x=\frac{8}{7}\\\frac{5}{8}x=\frac{-20}{7}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{64}{35}\\x=\frac{-32}{7}\end{cases}}}\)
Vậy \(x\in\left\{\frac{64}{35};\frac{-32}{7}\right\}\)
Bài 1 :
a) \(\left(\frac{2}{5}-\frac{5}{8}\right):\frac{11}{30}+\frac{1}{8}\)
\(=\frac{-9}{40}:\frac{11}{30}+\frac{1}{8}\)
\(=\frac{-27}{44}+\frac{1}{8}\)
\(=\frac{-43}{88}\)
\(18^{20}.45^5.5^{25}.8^{10}\)
\(=3^{40}.2^{20}.5^5.3^{10}.5^{25}.2^{30}\)
\(=3^{50}.2^{50}.5^{30}\)
\(=6^{50}.5^{30}\)
\(=\left(6^5\right)^{10}.\left(5^3\right)^{10}\)
\(=\left(6^5.5^3\right)^{10}\)
\(\left(x^2y\right)^5.\left(x^2.y^2\right)^7.\left(x.y\right)^6.x^3\)
\(=x^{10}.y^5.x^{14}.y^{14}.x^6.y^3.x^3\)
\(=x^{33}.y^{22}\)
\(=\left(x^3\right)^{11}.\left(y^2\right)^{11}\)
\(=\left(x^3.y^2\right)^{11}\)
\(2^7.3^8.4^9.9^8\)
\(=2^7.3^8.2^{18}.3^{16}\)
\(=2^{25}.3^{24}\)( mk chỉ làm được đến thế thôi )
Tham khảo nhé~
a) \(18^{20}.45^5.5^{25}.8^{10}\)
\(=\left(2.3^2\right)^{20}.\left(3^2.5\right)^5.5^{25}.\left(2^3\right)^{10}\)
\(=2^{20}.3^{40}.3^{10}.5^5.5^{25}.2^{30}\)
\(=2^{50}.3^{50}.5^{30}\)
\(=6^{50}.5^{30}\)
\(=\left(6^5\right)^{10}.\left(5^3\right)^{10}\)
\(=7776^{10}.125^{10}\)
\(=972000^{10}\)
b ) \(\left(x^2y\right)^5.\left(x^2.y^2\right)^7.\left(xy\right)^6.x^3\)
\(=x^{10}.y^5.x^{14}.y^{14}.x^6.y^6.x^3\)
\(=x^{33}.y^{25}\)
\(=x^{25}.y^{25}.x^8\)
\(=...\)
c) \(2^7.3^8.4^9.9^8\)
\(=2^7.3^8.\left(2^2\right)^9.\left(3^2\right)^8\)
\(=2^7.3^8.2^{18}.3^{16}\)
\(=2^{25}.3^{24}\)
\(=...\)( Câu c này hình như đề bài sai sót . Không chuyển thành lũy thừa được )
a)\(\left(x-32\right):16-13=48\)
\(\left(x-32\right):16=48+13\)
\(x+32=61.16\)
\(x+32=976\)
\(x=976-32\)
\(x=944\)
b) \(-2\left(2x-8\right)+\left(4-2x\right)=-72\)
\(-4x+16+4-2x=-72\)
\(-4x-2x=-72-16-4\)
\(-6x=-92\)
\(x=\frac{-92}{-6}=\frac{46}{3}\)
hok tốt!!
( x - 32 ) : 16 - 13 = 48
=> ( x - 32 ) : 16 = 48 + 13
=> ( x - 32 ) : 16 = 61
=> x - 32 = 61 . 16
=> x - 32 = 976
=> x = 976 + 32
=> x = 1008