Tìm x biết : x : (-2)^5=(-2)^3 bằng
A.(-2)^8 B.(-2)^2 C.(-2)^15 D.(-2)^7
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a: 2x(x+1)-135=-200
=>2(x^2+x)=-65
=>2x^2+2x+65=0
=>x^2+x+32,5=0
=>x^2+x+0,25+32,25=0
=>(x+0,5)^2+32,25=0(vô lý)
b: 4x-5(x-1)+15=13
=>4x-5x+5=-2
=>5-x=-2
=>x=5+2=7
c: 2/3x-1/4=3/5-7/8
=>2/3x=3/5-7/8+1/4=24/40-35/40+10/40=-1/40
=>x=-1/40:2/3=-1/40*3/2=-3/80
d: 1/2(2x-3)+105/2=-137/2
=>1/2(2x-3)=-137/2-105/2=-242/2=-121
=>2x-3=-242
=>2x=-239
=>x=-239/2
Câu 3:
Chiều rộng là 90x3/5=54(m)
Chu vi là (90+54)x2=288(m)
Câu 4:
Chiều rộng là 60x3/5=36(m)
Chu vi là (60+36)x2=192(m)
Diện tích là 60x36=2160(m2)
Bài 1:
a) \(\dfrac{9}{20}-\dfrac{8}{15}\times\dfrac{5}{12}\)
\(=\dfrac{9}{20}-\dfrac{2}{9}\)
\(=\dfrac{41}{180}\)
b) \(\dfrac{2}{3}\div\dfrac{4}{5}\div\dfrac{7}{12}\)
\(=\dfrac{2}{3}\times\dfrac{5}{4}\times\dfrac{12}{7}\)
\(=\dfrac{5}{6}\times\dfrac{12}{7}\)
\(=\dfrac{10}{7}\)
c) \(\dfrac{7}{9}\times\dfrac{1}{3}+\dfrac{7}{9}\times\dfrac{2}{3}\)
\(=\dfrac{7}{9}\times\left(\dfrac{1}{3}+\dfrac{2}{3}\right)\)
\(=\dfrac{7}{9}\times1\)
\(=\dfrac{7}{9}\)
Bài 2:
a) \(2\times\left(x-1\right)=4026\)
\(\left(x-1\right)=4026\div2\)
\(x-1=2013\)
\(x=2014\)
Vậy: \(x=2014\)
b) \(x\times3,7+6,3\times x=320\)
\(x\times\left(3,7+6,3\right)=320\)
\(x\times10=320\)
\(x=320\div10\)
\(x=32\)
Vậy: \(x=32\)
c) \(0,25\times3< 3< 1,02\)
\(\Leftrightarrow0,75< 3< 1,02\) ( S )
=> \(0,75< 1,02< 3\)
\(-4+x=-4+7\)
\(\Rightarrow x=-4+7+4\)
\(\Rightarrow x=7\)
\(\left(-3\right)-\left(-5-x\right)=-15+\left(-6+15\right)\)
\(\Rightarrow x=-15-6+15+3-5\)
\(\Rightarrow x=-8\)
\(-\left(x+2\right)+2=\left(8-15\right)+15\)
\(\Rightarrow-x+2+2=-7+15\)
\(\Rightarrow-x=-7+15-2-2\)
\(\Rightarrow x=-4\)
\(4+\left(x-4\right)=-\left(11-2\right)+\left(11+4\right)\)
\(\Rightarrow4+x-4=-11+2+11+4\)
\(\Rightarrow x=-11+2+11+4-4+4\)
\(\Rightarrow x=6\)
a) -4 + x = -4 + 7 b) (-3) - (-5-x) = -15 + (-6+15)
-4 + x + 4 - 7 = 0 (-3) + 5 + x = -6
x - 7 = 0 2 + 6 = -x
x= 7 8 = -x
Vậy x= 7 x= -8 =) Vậy x= -8
c) -(x+2)+2=(8-15)+15 d) 4+(x-4)= -(11-2) + (11+4 )
-x - 2 + 2 = 8 4+x-4 = 6
-x = 8 x=6
x= -8 Vậy x=6
Vậy x= -8
a) \(15-5\left|x+4\right|=-12-3\)
\(\Leftrightarrow5\left|x+4\right|=30\)
\(\Leftrightarrow\left|x+4\right|=6\)
\(\Leftrightarrow\orbr{\begin{cases}x+4=6\\x+4=-6\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=-10\end{cases}}\)
b) \(\left(4x-8\right)\left(7-x\right)=0\Leftrightarrow\orbr{\begin{cases}4x-8=0\\7-x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=7\end{cases}}\)
c) \(\left(x^2-36\right)\left(x^2+5\right)=0\Rightarrow\left(x-6\right)\left(x+6\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-6=0\\x+6=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=6\\x=-6\end{cases}}\)
d) \(-3\left(x+7\right)-11=2\left(x+5\right)\)
\(\Leftrightarrow-3x-32=2x+10\)
\(\Leftrightarrow5x=-42\Rightarrow x=-\frac{42}{5}\)
a, (6/11+5/11)x3/17
c1:=1x3/17
=3/17
c2:=6/11x3/17+5/11x3/17
=18/197+15/187
=33/187
=3/17
b,3/5x7/9-3/5x2/9
c1:=21/45-6/45
=15/45
=1/3
c2:=3/5x(7/9-2/9)
=3/5x5/9
=1/3
c,( 6/7-4/7):2/5
c1:=2/7:2/5
=2/7x5/2
=5/7
c2,6/7:2/5-4/7:2/5
=6/7x5/2-4/7x5/2
=15/7-10/7
=5/7
d,8/15:2/11+7/15:2/11
c1:=(8/15+7/15):2/11
=1x11/2
=11/2
c2:=8/15x11/2+7/15x11/2
=88/30+77/30
=165/30
=11/2
a) (\(\frac{6}{11}\) + \(\frac{5}{11}\)) x \(\frac{3}{17}\)= \(\frac{11}{11}\) x \(\frac{3}{17}\)= \(1\) x\(\frac{3}{17}\)= \(\frac{3}{17}\)
b) \(\frac{3}{5}\)x\(\frac{7}{9}\)- \(\frac{3}{5}\)x \(\frac{2}{9}\) = \(\frac{3}{5}\)x (\(\frac{7}{9}\)- \(\frac{2}{9}\))= \(\frac{3}{5}\) x \(\frac{5}{9}\)= \(\frac{3}{9}\)
c) (\(\frac{6}{7}\)- \(\frac{4}{7}\)) : \(\frac{2}{5}\)= \(\frac{2}{7}\) x \(\frac{5}{2}\)= \(\frac{5}{7}\)
d) \(\frac{8}{15}\) : \(\frac{2}{11}\) + \(\frac{7}{15}\): \(\frac{2}{11}\)= ( \(\frac{8}{15}\)+ \(\frac{7}{15}\)) x \(\frac{11}{2}\)= 1 x \(\frac{11}{2}\)= \(\frac{11}{2}\)
Chúc học tốt nha!
A nha bn