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\(\dfrac{4}{3.5}+\dfrac{8}{5.9}+\dfrac{12}{9.15}+...+\dfrac{32}{x\left(x+16\right)}=\dfrac{16}{15}\)
\(2.\left(\dfrac{2}{3.5}+\dfrac{4}{5.9}+\dfrac{6}{9.15}+..+\dfrac{16}{X.\left(X+16\right)}\right)=\dfrac{16}{15}\)
\(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{15}+...+\dfrac{1}{X}-\dfrac{1}{X+16}=\dfrac{8}{15}\)
\(\dfrac{1}{X+16}=\dfrac{1}{3}-\dfrac{8}{15}\)
\(\dfrac{1}{X+16}=\dfrac{-1}{5}\)
\(X+16=-5\)
\(X=-21\)
a) \(39-x+\left[28-\left(48-2\cdot13\right)\right]=-15\)
\(39-x+\left[28-\left(48-26\right)\right]=-15\)
\(39-x+\left[28-24\right]=-15\)
\(39-x+4=-15\)
\(39-x=-15-4=-19\)
\(x=39-\left(-19\right)=58\)
xong ý A rùi
b) \(\left(-45\right)-x-\left[126-\left(52-165\right)\right]=85-22\)
\(\left(-45\right)-x-\left[125-\left(-113\right)\right]=63\)
\(\left(-45\right)-x-238=63\)
\(\left(-45\right)-x=63+238=301\)
\(x=\left(-45\right)-301=-346\)
xong ý B rùi
a) -2x - ( x - 17 ) = 34 - ( -x + 25 )
<=> -2x - x + 17 = 34 + x -25
<=> -2x -x - x = 34 - 25 - 17
<=> -4x = -8
<=> x = 2
b) 3x - 32 > -5x + 1
<=> 3x + 5x >1 + 32
<=> 8x > 33
<=> x > \(\dfrac{33}{8}\)
c) 17 + 3 . ( -16x - 37 ) = 2x + 43 - 4x
<=> 17 + ( -48x - 111 ) = -2x + 43
<=> 17 - 48x - 111 = -2x + 43
<=> -48x +2x = 43 - 17 + 111
<=> -46x = 137
<=> x = \(\dfrac{137}{-46}\)
a) 320 x 63 - 16 x 20 + 32 x 370
= 320 x 63 - 320 x + 320 x 37
= 320 x ( 63 - 1 + 37 )
= 320 x 99
= 320 x ( 100 - 1 )
= 320 x 100 - 320
= 32000 - 320 = 31 680
b) 35 x 61 + 215 x 5 + 35 x 39 + 57 x 25
= 5 x 427 + 5 x 215 + 5 x 273 + 5 x 285
= 5 x ( 427 + 215 + 273 + 285 )
= 5 x 1200 = 6000
c) 34 x 24 - 94 x 6 + 83 x 48 - 47 x 88
= 204 x 4 - 4 x 141 + 996 x 4 - 1034 x 4
= 4 x ( 204 - 141 + 996 - 1034 )
= 4 x 25 = 100
a) 461 + (x – 45) = 387
x – 45 = 387 – 461
x – 45 = -74
x = -74 + 45
x = -29
Vậy x = -29
b) 11 – (-53 + x) = 97
-53 + x = 11 – 97
-53 + x = -86
x = -86 – (-53)
x = -33
Vậy x = -33
c) -(x + 84) + 213 = -16
-(x + 84) = -16 – 213
-(x + 84) = -229
-x – 84 = -229
-x = -229 + 84
-x = -145
\(\Rightarrow\)x = 145
Vậy x = 145
Tick cho mình nhé!!! 
34(-84) + 17(-32)
= -2856 + (-544)
= -2856 - 544
= -3400
ủng hộ nha. tớ đang âm
34 x ( - 84 ) + 17 x ( - 32 )
=[ 34 + ( - 32 ) ] x [ ( - 84 ) + 17 ]
=2 x ( - 67 )
= - 134
mk cx ko chắc lắm nha! nếu sai thì thôi hén
tk mk nha ( nếu đúng nhé ! )
=16x2x(-39) + 16x(-22)
= 16 x (-78) + 16 x (-22)
= 16 x ( -78 + (-22)
= 16 x (-100)
= -1600
\(17\times2\times\left(-84\right)+17\times\left(-22\right)\)
\(17\times\left(-168\right)+17\times\left(-22\right)\)
\(17\times\left(-168+\left(-22\right)\right)\)
\(17\times\left(-190\right)\)
-3230