48:4=...
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\(\frac{48}{x+4}+\frac{48}{x-4}=5\)
\(\Leftrightarrow\frac{48\left(x-4\right)}{\left(x-4\right)\left(x+4\right)}+\frac{48\left(x+4\right)}{\left(x+4\right)\left(x-4\right)}=\frac{5\left(x+4\right)\left(x-4\right)}{\left(x-4\right)\left(x+4\right)}\)
\(\Rightarrow48\left(x-4\right)+48\left(x+4\right)=5\left(x-4\right)\left(x+4\right)\)
\(\Leftrightarrow48x-192+48x+192-5\left(x+4\right)\left(x-4\right)=0\)
\(\Leftrightarrow96x-5\left(x^2-4\right)=0\)
\(\Leftrightarrow96x-5x^2+20=0\)
Giải phương trình bậc hai tìm x
(4x - 2008 ) : 4 - 48 = 48
( 4x - 2008 ) : 4 = 48 +48
(4x - 2008 ) : 4 = 96
4x - 2008 = 96.4
4x - 2008 = 384
4x = 384 + 2008
4x = 2382
x = 598
Tk mk nha
tính giá trị biểu thức:
48 x 55 +12 x 4 + 48= 2040+48
= 2088+48
=2136
tính nhẩm:
48 x 55 +12 x 4 + 48= 2136
(4x-2008):4-48=48
(4x-2008):4=48+48
(4x-2008):4=96
4x-2008 =96.4
4x-2008 =384
4x =384+2008
4x =2392
x =2392:4
x =598
Vậy x = 598
\(\left(4x-2008\right):4-48=48\)
\(\Rightarrow\left(4x-2008\right):4=48+48\)
\(\Rightarrow\left(4x-2008\right):4=96\)
\(\Rightarrow\left(4x-2008\right)=96.4\)
\(\Rightarrow\left(4x-2008\right)=384\)
\(\Rightarrow4x=384+2008\)
\(\Rightarrow4x=2392\)
\(\Rightarrow x=2396:4\)
\(\Rightarrow x=598\)
\(A=\frac{2}{2\cdot3\cdot4}+\frac{2}{3\cdot4\cdot5}+...+\frac{2}{47\cdot48\cdot49}+\frac{2}{48\cdot49\cdot50}\)
\(A=\frac{1}{2\cdot3}-\frac{1}{3\cdot4}+\frac{1}{3\cdot4}-\frac{1}{4\cdot5}+...+\frac{1}{47\cdot48}-\frac{1}{48\cdot49}+\frac{1}{48\cdot49}-\frac{1}{49\cdot50}\)
\(A=\frac{1}{2\cdot3}-\frac{1}{49\cdot50}\)
\(A=\frac{1}{6}-\frac{1}{2450}\)
\(A=\frac{611}{3675}\)
mong giúp đc bn.thk cho mk
a) 13.(23+22)-3.(17+28)
= 13.45 - 3.45
= 45(13-3)
= 45.10 =450
b) -48+48.(-78)+48(-21)
= -48 + 48(-78 - 21)
= -48 + 48.(-99)
= -48 + ( -4752)
= -4800
c) 135.(171-123)-171.(135-123)
= 135.171 - 135.123 - 171.135 + 171.123
= (135.171 - 171.135) - (135.123 - 171.123)
= - 123(135 - 171) = (-123).(-36)= 4428
9*8*48+7*4*48+72*52+2*52*14
=72*48+28*48+72*52+28*52
=72 * ( 48 + 52 ) + 28 * ( 48 + 52 )
=72 * 100 + 28 * 100
=100 * ( 72 + 28 )
= 100 * 100
=10000
9 x 8 x 48 + 7 x 4 x 48 + 72 x 52 + 2 x 52 x 14
= 72 x 48 + 28 x 48 + 72 x 52 + 2 x 14 x 52
= ( 72 + 28 ) x 48 + 72 x 52 + 28 x 52
= ( 72 + 28 ) x 48 + ( 72 + 28 ) x 52
= 100 x 48 + 100 x 52
= 100 x ( 48 + 52 )
= 100 x 100
= 10000
1) $(-81)\cdot27-3^4\cdot(-77)$
$=(-81)\cdot27-81\cdot(-77)$
$=-81\cdot[27+(-77)]$
$=-81\cdot(27-77)$
$=-81\cdot(-50)$
$=81\cdot50$
$=4050$
2) $(-16)\cdot32-(-4)^2\cdot18$
$=(-16)\cdot32-16\cdot18$
$=-16\cdot(32+18)$
$=-16\cdot50$
$=-800$
3) $(-2)^4\cdot289-16\cdot189$
$=16\cdot289+16\cdot(-189)$
$=16\cdot[289+(-189)]$
$=16\cdot(289-189)$
$=16\cdot100$
$=1600$
4) $41\cdot(-18)+41\cdot(-81)-41$
$=1\cdot(-18)+41\cdot(-81)+41\cdot(-1)$
$=41\cdot[(-18)+(-81)+(-1)]$
$=41\cdot(-18-81-1)$
$=41\cdot(-99-1)$
$=41\cdot(-100)$
$=-4100$
5) $17\cdot(-37)-23\cdot37-46\cdot(-37)$
$=17\cdot(-37)+23\cdot(-37)-46\cdot(-37)$
$=-37\cdot(17+23-46)$
$=-37\cdot(40-46)$
$=-37\cdot(-6)$
$=37\cdot6$
$=222$
6) $-48+48\cdot(-78)+48\cdot(-21)$
$=48\cdot(-1)+48\cdot(-78)+48\cdot(-21)$
$=48\cdot[(-1)+(-78)+(-21)]$
$=48\cdot(-1-78-21)$
$=48\cdot(-79-21)$
$=48\cdot(-100)$
$=-4800$
7) $29\cdot(-13)+27\cdot(-29)+(-14)\cdot(-29)$
$=-29\cdot13+27\cdot(-29)+(-14)\cdot(-29)$
$=-29\cdot[13+27+(-14)]$
$=-29\cdot(40-14)$
$=-29\cdot26$
$=-754$
$\text{#}Toru$
48:4 = 12
12 12 12 12 12 1 2