Đề 3:Bài 1 :Thực hiện phép tính
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Lời giải:
$=17.85+15.17-2^{45}=17(85+15)-2^{45}=17.100-2^{45}$
$=1700-2^{45}$
Số $2^{45}$ quá lớn để hiển thị nên để kết quả như trên là hợp lý nhất rồi bạn.
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Sửa đề
a) 37.24 + 37.76 + 63.79 + 21.63
= 37.(24 + 76) + 63.(79 + 21)
= 37.100 + 63.100
= 100.(37 + 63)
= 100.100
= 10000
b) 49 + (139 - 172 + 99) - (139 + 199 - 172)
= 49 + 139 - 172 + 99 - 139 - 199 + 172
= 49 + (139 - 139) + (172 - 172) + (99 - 199)
= 49 + 0 + 0 - 100
= -51
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\(a,8\times5+(-3)\times9=40+(-27)=13\)
\(b,\frac{2}{5}+\frac{1}{5}\times\left[\frac{-3}{4}\right]\)
\(=\frac{2}{5}+\frac{-3}{20}\)
\(=\frac{8}{20}+\frac{-3}{20}=\frac{5}{20}=\frac{1}{4}\)
\(c,2:\left[\frac{1}{2}-\frac{2}{3}\right]=2:\left[\frac{3}{6}-\frac{4}{6}\right]=2:\frac{-1}{6}=2\times\frac{6}{-1}=-12\)
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\(2x\left(x+3\right)-x\left(2x-1\right)\)
\(=2x^2+6x-2x^2+x\)
\(=7x\)
\(2x\left(x+3\right)-x\left(2x-1\right)\)
\(=2x^2+6x-2x^2+x=7x\)
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sẵn tiện giúp em luôn nha :
( -17)+ 14+ (-12)
5 mũ 10 : 5 mũ 8 +60 : 12+(-10)
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Bài 1:
b: \(=\dfrac{x+3-4-x}{x-2}=\dfrac{-1}{x-2}\)
Bài 2:
a: \(=\dfrac{x+1}{2\left(x+3\right)}+\dfrac{2x+3}{x\left(x+3\right)}\)
\(=\dfrac{x^2+x+4x+6}{2x\left(x+3\right)}=\dfrac{x^2+5x+6}{2x\left(x+3\right)}=\dfrac{x+2}{2x}\)
d: \(=\dfrac{3}{2x^2y}+\dfrac{5}{xy^2}+\dfrac{x}{y^3}\)
\(=\dfrac{3y^2+10xy+2x^3}{2x^2y^3}\)
e: \(=\dfrac{x^2+2xy+x^2-2xy-4xy}{\left(x+2y\right)\left(x-2y\right)}=\dfrac{2x^2-4xy}{\left(x+2y\right)\cdot\left(x-2y\right)}=\dfrac{2x}{x+2y}\)
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\(\left\{210:\left[16+3.\left(6+3.2^2\right)\right]\right\}-3\)
\(=\left\{210:\left[16+3.\left(6+3.4\right)\right]\right\}-3\)
\(=\left\{210:\left[16+3.\left(6+12\right)\right]\right\}-3\)
\(=\left\{210:\left[16+3.18\right]\right\}-3\)
\(=\left\{210:\left[16+54\right]\right\}-3\)
\(=\left\{210:70\right\}-3\)
\(=3-3\)
\(=0\)
Bài 1 :
a) -14 + ( -24 ) = -38
b) \(\frac{5}{17}+\frac{2}{17}=\frac{17}{17}=1\)
Bài 2 :
a) 11 . 62 + ( - 12 ) . 11 + 50 . 11
= 11 . ( 62 - 12 + 50 )
= 11 . 100 = 1100
b) \(\frac{5}{13}+\frac{-5}{7}+\frac{-20}{41}+\frac{8}{13}+\frac{-21}{41}\)
\(=\left(\frac{5}{13}+\frac{8}{13}\right)+\left(\frac{-20}{41}+\frac{-21}{41}\right)+\frac{-5}{7}\)
\(=1+\left(-1\right)+\frac{-5}{7}=\frac{-5}{7}\)Bài 3 :
Bài 3 :
a) \(x+\frac{4}{7}=\frac{11}{7}\)
\(\Rightarrow x=\frac{11}{7}-\frac{4}{7}=\frac{7}{7}=1\)
b) \(x-\frac{4}{15}=\frac{-3}{10}\)
\(\Rightarrow x=\frac{-3}{10}+\frac{4}{15}=\frac{-1}{30}\)
Bài 1
a) \(-14+\left(-24\right)\)
\(=-14-24\)
\(=-38\)
b) \(\frac{5}{17}\)+ \(\frac{12}{17}\)
\(=\) \(\frac{5+12}{17}\)
\(=\) \(1\)
\(~~HT~~\)