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222-9+11+12:2*14+14 = ? ( )

## Toán Lớp 6: a)196:4-12.(-15) b)2^2.5+(49-17^2 c)29.(15-34)-15.(29-34) d)(705-x):3=4221:21 e)100-7(x-5)=58 g)(2x-1)^3=125 h)Cho tổng A=2^0+2^1+2^2+2

Toán Lớp 6: a)196:4-12.(-15)
b)2^2.5+(49-17^2
c)29.(15-34)-15.(29-34)
d)(705-x):3=4221:21
e)100-7(x-5)=58
g)(2x-1)^3=125
h)Cho tổng A=2^0+2^1+2^2+2^3+2^4+2^5+….+2^100

1. $\text{a}$$\text{,} \text{196} \text{:} \text{4} \text{-} \text{12} \text{.} \text{(-15)} \text{=} \text{49} + \text{12} \text{.} \text{15} \text{=} \text{49} \text{+} \text{180} \text{=} \text{229} \text{b}$$\text{,}$ $\text{2^2}$ $\text{.}$ $\text{5}$ $\text{+}$ $\text{(}$$\text{49} \text{-} \text{17^2}$$\text{)}$
$\text{=}$ $\text{4}$ $\text{.}$ $\text{5}$ $\text{+}$ $\text{(}$$\text{49} \text{-} \text{289}$$\text{)}$
$\text{=}$ $\text{20}$ $\text{+}$ $\text{(}$$\text{-240}$$\text{)}$
$\text{=}$ $\text{20}$ $\text{-}$ $\text{240}$
$\text{=}$ $\text{-220}$
$\text{c}$$\text{,} \text{29.(15 – 34) – 15.(29 – 34)} \text{=} \text{29.15 – 29.34 – 15.29 + 15.34} \text{=} \text{- 29.34 + 15.34} \text{=} \text{(- 29 + 15).34} \text{=} \text{(- 14).34} \text{=} \text{- 476} \text{d}$$\text{,}$ $\text{(705 – x):3= 4221:21}$
$\Rightarrow$ $\text{705 – x= 4221:7}$
$\Rightarrow$ $\text{705 – x= 603}$
$\Rightarrow$ $\text{x= 705-603}$
$\Rightarrow$ $\text{x= 102}$
$\text{e, 100 – 7(x – 5) = 58}$
$\text{$\Rightarrow$7(x – 5) = 100 – 58}$
$\text{$\Rightarrow$7(x – 5) = 42}$
$\text{$\Rightarrow$x – 5 = 6}$
$\text{$\Rightarrow$x = 11}$
$\text{g,$(2x – 1)^3$= 125}$
$\text{$\Rightarrow(2x – 1)^3$=$5^3$}$
$\text{$\Rightarrow$2x – 1 = 5 }$
$\text{$\Rightarrow$2x = 6 }$
$\text{$\Rightarrow$x = 3 }$
$\text{h, A =$2^0$+$2^1$+$2^2$+ ….. +$2^{99}$+$2^{100}$}$
$\text{$\Rightarrow$2A =$2^1$+$2^2$+$2^3$+ ….. +$2^{100}$+$2^{101}$}$
$\text{$\Rightarrow$A = 2A – A = ($2^1$+$2^2$+$2^3$+ ….. +$2^{100}$+$2^{101}$) – ($2^0$+$2^1$+$2^2$+ ….. +$2^{99}$+$2^{100}$) }$
$\text{$\Rightarrow$A = 2A – A =$2^{101}$–$2^0$=$2^{101}$– 1 }$