4 | + | 4 | + … + | 4 | = | |
8 x 10 | 10 x 12 | 206 x 208 |
Tim X
3) -12 + (2x – 9) + x= 0
4) 11 + (15 - x) = 1
5) 4 - (27 - 3) = x - (13 - 4)
6) 8 - (x - 10) = 23 - (- 4 +12)
7) 105 – 5(10 – 5x) = -20
8) (x -1)(8-2x)(3x+123) = 0
9) (x2 - 25)(x+ 10) = 0
10) x(x2+5) =
3) \(-12+2x-9+x=0\\ -21+3x=0\\ 3x=21\\ x=7\)
4)
\(11+\left(15-x\right)=1\)
\(15-x=1-11\)
\(15-x=-10\)
\(x=15-\left(-10\right)\)
\(x=25\)
5)
\(4-\left(27-3\right)=x-\left(13-4\right)\)
\(4-24=x-9\)
\(x-9=-20\)
\(x=-20+9\)
\(x=-11\)
\(3.-12+\left(2x-9\right)+x=0.\)
\(\Leftrightarrow-12+2x-9+x=0.\Leftrightarrow3x=21.\Leftrightarrow x=7.\)
Vậy \(x=7.\)
\(4.11+\left(15-x\right)=1.\Leftrightarrow11+15-x=1.\Leftrightarrow26-x=1.\Leftrightarrow x=25.\)
Vậy \(x=25.\)
\(5.4-\left(27-3\right)=x-\left(13-4\right).\Leftrightarrow4-24=x-9.\Leftrightarrow-20=x-9.\Leftrightarrow x=-11.\)
Vậy \(x=-11.\)
\(6.8-\left(x-10\right)=23-\left(-4+12\right).\Leftrightarrow8-x+10=23-8.\Leftrightarrow18-x=15.\Leftrightarrow x=3.\)
Vậy \(x=3.\)
\(7.105-5\left(10-5x\right)=-20.\Leftrightarrow105-50+25x=-20.\Leftrightarrow25x=-75.\Leftrightarrow x=-3.\)
Vậy \(x=-3.\)
\(8.\left(x-1\right)\left(8-2x\right)\left(3x+123\right)=0.\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0.\\8-2x=0.\\3x+123=0.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1.\\x=4.\\x=-41.\end{matrix}\right.\)
Vậy \(x\in\left\{1;4;-41\right\}.\)
\(9.\left(x^2-25\right)\left(x+10\right)=0.\)
\(\Leftrightarrow\left(x-5\right)\left(x+5\right)\left(x+10\right)=0.\)
\(\Leftrightarrow\left[{}\begin{matrix}x-5=0.\\x+5=0.\\x+10=0.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5.\\x=-5.\\x=-10.\end{matrix}\right.\)
Vậy \(x\in\left\{5;-5;-10\right\}.\)
\(10.x\left(x^2+5\right)=0.\Leftrightarrow x=0.\)
Bài 1: Tìm x [GIÚPPPPPPPPPPPPPPPPPPP]
1) 5 – (10 – x) = 7
2) - 32 - (x – 5) = 0
3) -12 + (2x – 9) + x= 0
4) 11 + (15 - x) = 1
5) 4 - (27 - 3) = x - (13 - 4)
6) 8 - (x - 10) = 23 - (- 4 +12)
7) 105 – 5(10 – 5x) = -20
8) (x -1)(8-2x)(3x+123) = 0
9) (x2 - 25)(x+ 10) = 0
10) x(x2+5) = 0
\(1\)) \(5-\left(10-x\right)=7\)
\(10-x=5-7\)
\(10-x=-2\)
\(x=10-\left(-2\right)\)
\(x=12\)
\(2\)) \(-32-\left(x-5\right)=0\)
\(x-5=-32-0\)
\(x-5=-32\)
\(x=-32+5\)
\(x=-27\)
1)10-x=5-7
x=10-(-2)
x=12
2)x+5=0+32
x=32-5
x=27
3) -12+2x-9+x=0
-12+(2x+x-9)=0
3x-9=0+12
3x=12+9
x=21:3
x=7
4) 15-x=1-11
x=15-(-10)
x=25
5) 4-(27+3)=x-9
4-30=x-9
-26+9=x
x=-17
D= 2+4-6-8+10+12-14-16+18+20-22-24+...+205+206-207-208
Giúp mk với
D = 2 + 4 - 6 - 8 + 10 + 12 - 14 - 16 + 18 + 20 - 22 - 24 + ... + 205 + 206 - 207 - 208
D = ( 2 + 4 - 6 - 8 ) + ( 10 + 12 - 14 - 16 ) + ( 18 + 20 - 22 - 24 ) + ... + ( 205 + 206 - 207 - 208 )
D = ( -8 ) + ( -8 ) + ( -8 ) + ... + ( -8 )
D = ( -8 ) . 104
D = -832
Tính nhẩm:
3 x 4 = 12 2 x 5 = 5 x 3 = 4 x 2 =
12 : 3 = 10 : 2 = 15 : 3 = 8 : 2 =
12 : 4 = 10 : 5 = 15 : 5 = 8 : 4 =
Ta tính nhẩm như sau:
3x4=12 2x5=10 5x3=15 4x2=8
12:3=4 10:2=5 15:3=5 8:2=4
12:4=3 10:5=2 15:5=3 8:4=2
3x4 = 12 2x5 = 10 5x3 = 15 4x2 =8
12 : 3 = 4 10 : 2 = 5 15 : 3 = 5 8 : 2 = 4
12 : 4 =3 10 :5 = 2 15 : 5 = 3 8 : 4 = 2
1 x 2 + 2 x 4 + 3 x 6 + 4 x 8 + 5 x 10 / 3 x 4 + 6 x 8 + 9 x 12 + 12 x 16 + 15 x 20
Ta có :1.2+2.4+3.6+4.8+5.10/3.4+6.8+9.12+12.16+15.20=[1.2(1+4+9+...+25)]/[3.4(1+4+9+16)]
=(1.2)/(3.4)=2/12=1/6
CHÚC BẠN HỌC TỐT!!
cho tớ nhé!!!!
=2+8+18+32+50/12+48+108+192+300
=110/660
=0.166666667\
2. Tính bằng cách thuận tiện nhất :
a) 206 x 8 x 5
=
=
b) 246 x 81 + 246 x 18 + 246
=
=
c) 813 x 25 x 4 x 5
=
=
d) 17 x 513 – 17 x 10 – 17 x 3
=
=
đang cần bài trước 7h15 tối ngày 9/12/2021
Tôi hứa sẽ tik
tớ gửi bài làm vào phần bình luận câu dưới rồi nhé , tớ cũng không chắc đâu
X x 5/9 + 6 = 10 260 - 10 x X = 250
200 + X : 1/4 = 206 1/4 - X + 150 = 156
X : 8/9 - 7 = 42 X - 45 : 5 = 280
\(x\)x\(\frac{5}{9}+6=10\)
\(x\)x\(\frac{5}{9}=10-6\)
\(x\)x\(\frac{5}{9}=4\)
\(x=4:\frac{5}{9}\)
\(x=\frac{36}{5}\)
Mình nghĩ vậy
X x 5/9 + 6=10
X x5/9= 10 - 6
X x 5/9= 4
X = 4: 5/9
X = 36/5
200 + X : 1/4 = 206
X : 1/4 = 206 -200
X : 1/4 = 6
X = 6 x 1/4
X =3/2
X : 8/9 - 7 = 42
X: 8/9 = 42 - 7
X : 8/9 = 35
X = 35 x 8/9
X = 280/9
bạn trả lời những câu còn lại giống cách mình làm ba bài kia nha
chứ mình lười nhớt thây, gõ hết chắc gãy tay
Giải các bất phương trình sau:
a) \(\dfrac{x-2}{1007}+\dfrac{x-1}{1008}< \dfrac{2x-1}{2017}+\dfrac{2x-3}{2015}\)
b) \(\dfrac{3-x}{100}+\dfrac{4-x}{101}>\dfrac{10-2x}{204}+\dfrac{12-2x}{206}\)
a: =>\(\dfrac{2x-4}{2014}+\dfrac{2x-2}{2016}< \dfrac{2x-1}{2017}+\dfrac{2x-3}{2015}\)
=>\(\dfrac{2x-2018}{2014}+\dfrac{2x-2018}{2016}< \dfrac{2x-2018}{2017}+\dfrac{2x-2018}{2015}\)
=>2x-2018<0
=>x<2019
b: \(\Leftrightarrow\left(\dfrac{3-x}{100}+\dfrac{4-x}{101}\right)>\dfrac{5-x}{102}+\dfrac{6-x}{103}\)
=>\(\dfrac{x-3}{100}+\dfrac{x-4}{101}-\dfrac{x-5}{102}-\dfrac{x-6}{103}< 0\)
=>\(x+97< 0\)
=>x<-97
Đề bài là:Tìm x:(1/1*2+1/1*3+1/3*4+...+1/8*9+1/9*10)*100-(5/2÷(x+206/100)÷1/2)=89
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