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a: \(=-57\cdot75+57\cdot36-75\cdot36+75\cdot57\)
\(=36\left(57-75\right)=-18\cdot36=-648\)
b: \(=19+19\cdot42+19\cdot10\)
\(=19\cdot62=1178\)
Bài 1:Tính
a, \(-57\left(75-36\right)-75\left(36-57\right)-57\left(75-36\right)-75\left(36-57\right)\)
\(=-114\left(75-36\right)-150\left(36-57\right)\)
\(=-144.39-150.\left(-21\right)\)
\(=-5616+3150=-2466\)
b, \(19-42\left(-19\right)+38.5\)
\(=19+42.19+19.2.5\)
\(=19.\left(1+42+10\right)=19.53=1007\)
Chúc bạn học tốt!!!
Bài 1
a, 32.(-64) - 64. 68
= -64.(32 + 68)
= -64 .100
= - 6400
b, -54.76 + 12.(-76) - 76.34
= -76.(54 + 12 + 34)
= -76.100
= -7600
19- 42.(-19) + 38.5
= 19 + 42.19 + 19.2.5
= 19.(1 + 42 + 10)
= 19.53
= 1007
\(a,36.19+36.81\)
\(=36.\left(19+81\right)\)
\(=36.100\)
\(=3600\)
\(b,8.12.125.5\)
\(=\left(125.8\right)\left(12.5\right)\)
\(=1000.60\)
\(=60000\)
\(c,\)chịu
c,7 x 9 + 14 x 27 + 21 x 36 / 21 x 27 + 42 x 81 + 63 x 108
7 x 9 + 14 x 27 + 21 x 36 / 7 x 3 x 9 x 3 + 14 x 3 x 27 x 3 + 21 x 3 x 36 x 3
1 / 3 x 3 + 3 x 3 + 3 x 3
1 / 9 + 9 + 9
1 / 27
Bài 1:tính
a)65.(-19)+19.(-35)
=65.(-19)+(-19).35
=(-19).(65+35)
=(-19).100
=-1900
b)85.(35-27)-35.(85-27)
=85.35-85.27-35.85+35.27
=(85.35-35.85)+(-85.27+35.27)
=27.(-85+35)
=27.(-50)
=1350
c)47.(45-15)-47.(45+15)
=47.[(45-15)-(45+15)]
=47.[30-60]
=47.(-30)
=-1410
Bài2: Tìm các số nguyên x biết
a)(-2).(x+6)+6.(x-10)=8
-2x-12+6x-60=8
4x-72=8
4x=72+8
4x=50
x=\(\frac{25}{2}\)
b)(-4).(2x+9)-(-8x+3)-(x+13)=0
-6x-36+8x-3-x-13=0
x-41=0
x=41
Bài 1: Tính
a) \(65.\left(-19\right)+19.\left(-35\right)\)
= \(-1235+-665\)
= \(-1900\)
b) \(85.\left(35-27\right)-35.\left(85-27\right)\)
= \(-1350\)
c) \(47.\left(45-15\right)-47.\left(45+15\right)\)
=\(-1410\)
Bài 2: Tìm x:
\(\left(-2\right).\left(x+6\right)+6.\left(x-10\right)=8\)
\(x=20\)
mik ko chép lại đề, mik làm luôn:
a) x - \(\frac{31}{36}=\frac{-13}{38}\)
x = \(\frac{-13}{18}+\frac{31}{36}\)
\(x=\frac{5}{36}\)
b)\(2-x-\frac{3}{7}=\frac{9}{-21}\)
\(\frac{11}{7}-x=\frac{3}{7}\)
x = \(\frac{11}{7}-\frac{3}{7}\)
x = 8/7
c) x + 3/11 = 23/44
x = 23/44 - 3/11
x = 1/4
d) \(\frac{1}{12}-x=\frac{-11}{9}\)
x = \(\frac{1}{12}+\frac{11}{9}\)
x = 47/36
e) \(x-\frac{2}{3}=\frac{-17}{3}\)
x= -17/3 + 2/3
x = -5
f) \(x-\frac{1}{2}=\frac{11}{4}.\frac{3}{11}\)
x - 1/2 = 3/4
x = 3/4 + 1/2
x = 5/4
g) \(2x+\frac{3}{8}=\frac{-21}{32}.\frac{4}{7}\)
2x + 3/8 = -3 / 8
2x = -3/8 - 3/8
2x = -9/8
x = -9/8.1/2
x = -9/16
h) x - \(\frac{x}{3}=\frac{3}{57}.\frac{19}{12}\)
x - \(\frac{x}{3}=\frac{1}{12}\)
x = \(\frac{1}{12}+\frac{x}{3}\)
x = \(\frac{1+4x}{12}\)
=> 12x = 1+4x
12x - 4x = 1
8x = 1
x = 1/8
Bài 1:
\(a.\left(-356+57\right)-\left(27-356\right)=-356+57-27+356=\left(-356+356\right)+\left(57-27\right)=30\) \(b.125.\left(-24+24.225\right)=125.\left(-24+5400\right)=125.\left(-24\right)+125.5400=-3000+675000=672000\)
\(c.26.\left(-125\right)-125.\left(-36\right)=-125.\left(26-36\right)=-125.\left(-10\right)=1250\)
Bài 2:
\(a.\left(2x-4\right)^2=0\)
\(\Rightarrow2x-4=0\)
\(\Rightarrow2x=4\)
\(\Rightarrow x=2\)
\(b.\frac{x+5}{x+3}=\frac{x+3+2}{x+3}=\frac{x+3}{x+3}+\frac{2}{x+3}=1+\frac{2}{x+3}\)
Để (x+5) chia hết cho (x+3) thì 2 phải chia hết cho (x+3)
\(\Rightarrow x+3\inƯ\left(2\right)=\left\{\pm1;\pm2\right\}\)
\(x+3=1\Rightarrow x=-2\)
\(x+3=-1\Rightarrow x=-4\)
\(x+3=2\Rightarrow x=-1\)
\(x+3=-2\Rightarrow x=-5\)
Vậy \(x\in\left\{-2;-4;-1;-5\right\}\)
Bài 2:
a)\(\left(2x-4\right)^2=0\)
\(\Leftrightarrow2x-4=0\)
\(\Leftrightarrow2x=4\Leftrightarrow x=2\)
b)\(\frac{x+5}{x+3}=\frac{x+3+2}{x+3}=\frac{x+3}{x+3}+\frac{2}{x+3}=1+\frac{2}{x+3}\in Z\)
Suy ra \(2⋮x+3\Rightarrow x+3\inƯ\left(2\right)=\left\{1;-1;2;-2\right\}\)
\(\Rightarrow x\in\left\{-2;-4;-1;-5\right\}\)
a. x + 4 \(⋮\) x
Vì \(x⋮x\) mà x + 4 \(⋮\) x
nên x + 4 - x \(⋮\) x
=> 4 \(⋮\)x
=> x \(\in\) {1;2;4}
Bài 2: Tìm x
a, \(7x\left(x-10\right)=0\)
\(\Rightarrow x\left(x-10\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x-10=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=10\end{matrix}\right.\)
b, \(\left(4-x\right)\left(2x+6\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}4-x=0\\2x+6=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-3\end{matrix}\right.\)
c, \(-12\left(x-5\right)+7\left(3-x\right)=5\)
\(\Rightarrow-12x+60+21-7x=5\)
\(\Rightarrow-19x=5-60-21\)
\(\Rightarrow-19x=-76\Rightarrow x=4\)
Chúc bạn học tốt!!!