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Bài 2:
a: \(=248+2064-12-236\)
\(=12-12+2064=2064\)
b: \(=-298-302-300=-600-300=-900\)
c: \(=5-7+9-11+13-15=-2-2-2=-6\)
d: \(=456+58-456-38=20\)
a: =>25-4x=1
=>4x=24
hay x=6
b: =>2x-4=0
hay x=2
c: =>x-35=115
hay x=150
d: =>x-2=12
hay x=14
e: =>x-36=216
hay x=252
1)
a)
\(19\cdot64+76\cdot3\\ =\left(19\cdot60+19\cdot4\right)+\left(76\cdot30+76\cdot4\right)\\ =1216+2584=3800\)
b)
\(35\cdot12+65\cdot13\\ =\left(35\cdot10+35\cdot2\right)+\left(65\cdot10+65\cdot3\right)\\ =420+845=1265\)
c)
\(27\cdot27-25\cdot29\\ =\left(27\cdot30-27\cdot3\right)-\left(25\cdot30-25\right)\\ =729-725=4\)
\(a)13-\left(40-X\right)=35\)
\(\Leftrightarrow40-X=13-35\)
\(\Leftrightarrow40-X=-22\)
\(\Leftrightarrow X=40-\left(-22\right)\)
\(\Leftrightarrow X=62\)
Vậy \(X=62\)
\(b)14-3x\left(5-X\right)=8\)
\(\Leftrightarrow3x\left(5-X\right)=14-8\)
\(\Leftrightarrow3x\left(5-X\right)=6\)
\(\Leftrightarrow5-X=6:3\)
\(\Leftrightarrow5-X=3\)
\(\Leftrightarrow X=5-3\)
\(\Leftrightarrow X=2\)
Vậy \(X=2\)
\(c)\left(3X-2\right)x\left(5+X\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}3X-2=0\\5+X=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}3X=0+2\\X=0-5\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}3X=2\\X=-5\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}X=2:3\\X=-5\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}X=\frac{2}{3}\\X=-5\end{cases}}\)
Vậy \(X\in\left\{-5;\frac{2}{3}\right\}\)
\(d)\left(3X-6\right)x3=3^4\)
\(\Leftrightarrow\left(3X-6\right)x3=81\)
\(\Leftrightarrow3X-6=81:3\)
\(\Leftrightarrow3X-6=27\)
\(\Leftrightarrow3X=27+6\)
\(\Leftrightarrow3X=33\)
\(\Leftrightarrow X=33:3\)
\(\Leftrightarrow X=11\)
Vậy\(X=11\)
1: \(=75\left(27+25-2\right)=75\cdot50=3750\)
2: \(=15\left(23+37\right)+55=15\cdot60+55=955\)
3: \(=36\cdot14+36\cdot17+36\cdot69\)
\(=36\cdot100=3600\)
4: \(=200\cdot\left(32+68\right)=200\cdot100=20000\)
Thay \(x=-4\) vào pt elip ta được:
\(\frac{y^2}{9}=1-\frac{16}{25}=\frac{9}{25}\Rightarrow\left[{}\begin{matrix}y=\frac{9}{5}\\y=-\frac{9}{5}\end{matrix}\right.\)
\(\Rightarrow MN=2.\frac{9}{5}=\frac{18}{5}\)
Mk vừa trả lời câu này rồi mà,sao bị mất vậy?