b) 200 : (4 . 5\(^3\) – 20\(^2\) )
tính tổng
B= 7-7 mu 4 + 7 mu 4 -........+7 mu 301
A = 1 + 5 mũ 2 + 5 mu 4 + 5 mu 6 +.....+5 mu 200
tính
A= 1/7+1/7mu 2 + 1/7 mu 3+......+1/7mu 100
B=-4/5+4/5 mu 2 - 4/5 mu 3 + ....+4/5mu 200
tính A=25 mũ 8 + 25 mũ 4 + 25 mu 20 +......+25 mu 4 +1 / 25 mu 20 + 25 mu 28 + 25 mu 26 +.....= 25 mu 2 +1
7 × 3 mu x + 20 × 3 mu x = 3 mu 25
a, \(\sqrt{200}-\sqrt{32}+\sqrt{72}\)
b, \(4\sqrt{20}-3\sqrt{125}+5\sqrt{45}-15\sqrt{\dfrac{1}{5}}\)
c, \(\left(2\sqrt{8}+3\sqrt{5}-7\sqrt{2}\right)\left(72-5\sqrt{20}-2\sqrt{2}\right)\)
a) \(\sqrt{200}-\sqrt{32}+\sqrt{72}\)
\(=\sqrt{10^2\cdot2}-\sqrt{4^2\cdot2}+\sqrt{6^2\cdot2}\)
\(=10\sqrt{2}-4\sqrt{2}+6\sqrt{2}\)
\(=\left(10-4+6\right)\sqrt{2}\)
\(=12\sqrt{2}\)
b) \(4\sqrt{20}-3\sqrt{125}+5\sqrt{45}-15\sqrt{\dfrac{1}{5}}\)
\(=4\cdot2\sqrt{5}-3\cdot5\sqrt{5}+5\cdot3\sqrt{5}-3\sqrt{5}\)
\(=8\sqrt{5}-15\sqrt{5}+15\sqrt{5}-3\sqrt{5}\)
\(=\left(8-15+15-3\right)\sqrt{5}\)
\(=5\sqrt{5}\)
c) \(\left(2\sqrt{8}+3\sqrt{5}-7\sqrt{2}\right)\left(72-5\sqrt{20}-2\sqrt{2}\right)\)
\(=\left(2\cdot2\sqrt{2}+3\sqrt{5}-7\sqrt{2}\right)\left(72-5\cdot2\sqrt{5}-2\sqrt{2}\right)\)
\(=\left(3\sqrt{5}-3\sqrt{2}\right)\left(72-10\sqrt{5}-2\sqrt{2}\right)\)
A= 1-2+3-4+...+59-60
B= 17- {15-[23 -(5+4/3)]-13}+2/3
C=-3/20-3/200-3/2000-3/20000
A= 1-2+3-4+...+59-60
=(1-2)+(3-4)+...+(59-60)
=-1+(-1)+...+(-1)
=(-1)*30
= -30
Đáp án : -30
( 1- 2 ) + ( 3 - 4 ) + ....+( 59 - 60 )
= ( -1 ) + ( -1 ) + .....+ ( -1 )
= Từ 1 đến 60 có 60 số. Vậy có 30 tổng ( số hạng ).
=> Nên tổng trên có kết quả là : ( -1 ) * 30
= -30
Vậy đáp án là -30.
a) 79 . 23 + 21 . 23
b) 2. ( 6 . 42 – 85 : 5)
c) (-5) .8 . (-2) . 3
d) 200 +32 –( 50 +32 )
e) 3 . (-2)2 + 4 . (-5) +20
a) \(79.2^3+21.2^3\)
\(=\left(79+21\right).2^3=100.8\)
= 800
b) \(2.\left(6.4^2-85:5\right)\)
\(=2.\left(96-17\right)=2.79\)
= 158
c) (- 5) . 8 . (- 2) . 3
= \(\left[\left(-5\right).\left(-2\right)\right].\left(8.3\right)\)
= 10 . 24 = 240
d) 200 + 32 - (50 + 32)
= 200 + 32 - 50 - 32 (quy tắc mở ngoặc đổi dấu)
= 200 + (32 - 32) - 50
= 200 - 50 = 150
e) 3 . \(\left(-2\right)^2\) + 4 . (- 5) + 20
= 3 . 4 + 4 .(- 5) + 20
= 4 . (-2) + 20
= - 8 + 20 = 12
Chúc học tốt!!
a) 79. 23 + 21 . 23
= 79 . 8 + 21 . 8
= ( 79 + 21 ) . 8
= 100 . 8
= 800
b) 2. ( 6 . 42 - 85 : 5 )
= 2 . ( 6 . 16 - 17 )
= 2 . ( 96 - 17 )
= 2 . 17
= 34
c) (-5) . 8 . (-2) . 30
= (-40) . (-2) . 3
= 80 . 3
= 240
d) 200 + 32 - ( 50 + 32 )
= 232 - 82
= 150
e) 3. (-2)2 + 4. (-5) + 20
= 3. (-4) + 4 . ( -5) + 20
= (-12 ) + (-20) + 20
= (-12) + 0
= (-12)
\(a,79.2^3+21.2^3.\)
\(=\left(79+21\right)2^3.\)
\(=100.2^3=100.8=800.\)
\(b,2\left(6.4^2-85:5\right).\)
\(=2\left(6.16-17\right).\)
\(=2\left(96-17\right).\)
\(=2.81=162.\)
\(c,\left(-5\right).8.\left(-2\right).3.\)
\(=\left[\left(-5\right).\left(-2\right)\right].\left(8.3\right).\)
\(=10.24=240.\)
\(d,200+32-\left(50+32\right).\)
\(=200+32-50-32.\)
\(=\left(200-50\right)+\left(32-32\right).\)
\(=150+0=150.\)
\(e,3.\left(-2\right)^2+4.\left(-5\right)+20.\)
\(=3.4+4.\left(-5\right)+20.\)
\(=\left[3+\left(-5\right)\right]4+20.\)
\(=\left(-2\right).4+20.\)
\(=\left(-8\right)+20=12.\)
~ Học tốt ~
Tính
1) (- 2) . (- 7) . (- 5) 2) 15 – 22 + ( - 17)
3) 25. (- 4) – 20. (- 5) 4) 185 – (49 + 185)
5) ( -19 ) . (- 13) + 13 . (-29)
6)79 . 23 + 21 . 23 7) 2. ( 6 . 42 – 85 : 5)
8) (-5) .8 . (-2) . 3 9) 200 +32 –( 50 +32 )
10) 3 . (-2)2 + 4 . (-5) +20
1,-70 3,0 5,-130 7,158 9.150
2,-24 4,-49 6,800 8,240 10,12
TÝnh
1) (- 2) . (- 7) . (- 5) 2) 15 – 22 + ( - 17)
3) 25. (- 4) – 20. (- 5) 4) 185 – (49 + 185)
5) ( -19 ) . (- 13) + 13 . (-29)
6)79 . 23 + 21 . 23 7) 2. ( 6 . 42 – 85 : 5)
8) (-5) .8 . (-2) . 3 9) 200 +32 –( 50 +32 )
10) 3 . (-2)2 + 4 . (-5) +20
1) (- 2) . (- 7) . (- 5)=-70
2) 15 – 22 + ( - 17)=-24
3) 25. (- 4) – 20. (- 5)=0
4) 185 – (49 + 185)=-49
5) ( -19 ) . (- 13) + 13 . (-29)=-130
6)79 . 23 + 21 . 23 =2300
7) 2. ( 6 . 42 – 85 : 5)=470
8) (-5) .8 . (-2) . 3=240
9) 200 +32 –( 50 +32 )=150
10) 3 . (-2).2 + 4 . (-5) +20=-12
(những bài như thế này thì chỉ cần bấm máy tính là ra thôi bạn nhé)
Chúc bạn học tốt!
1 tính
a,( 17/20+19/21). 31/20 (17/20+19/21). (-31/20)
b, 3/4.15/2+15/8.(-3) + 199/200
c, (199/200+201/202+2015/2014). (1/2+2/3+ -7/6)
d, a(b+1/5) -a ( 6/5 + b ) với a= 2015/2015 ; b= 2000
a) 3(x+1) - 2 = 4
b) 5(x-2) + 20 = 45
c) 700 - 7 (x+2) = 140
d) 200 - 5 (2x+4) = 100
e) 5 (2x - 4) + 150 = 250
\(a,3\left(x+1\right)-2=4\)
\(\Leftrightarrow3\left(x+1\right)=6\)
\(\Leftrightarrow x+1=2\)
\(\Leftrightarrow x=1\)
Vậy x=1
Các câu còn lại lm tương tự nhé
\(3\left(x+1\right)-2=4\)
<=> \(3x+3-2=4\)
<=> \(3x=3\)
<=> \(x=1\)
\(5\left(x-2\right)+20=45\)
<=> \(5x-10=25\)
<=> \(x=7\)
\(700-7\left(x+2\right)=140\)
<=> \(7x+14=560\)
<=> \(7x=546\)
<=> \(x=78\)
\(200-5\left(2x+4\right)=100\)
<=> \(10x+20=100\)
<=> \(x=8\)
\(5\left(2x-4\right)+150=250\)
<=> \(10x-20=100\)
<=> \(x=12\)
học tốt
a) 3(x + 1) - 2 = 4 b) 5(x-2) + 20 = 45 c ) 700 - 7 ( x + 2 ) = 140 d) 200 - 5 ( 2x +4 ) = 100
3(x + 1 ) = 4 + 2 5 ( x -2 ) = 45 - 20 7 ( x + 2 ) = 700 - 140 5 ( 2x + 4 ) = 200 - 100
3( x + 1 ) = 6 5 ( x - 2 ) = 25 7 ( x + 2 ) = 560 5 ( 2x + 4 ) = 100
x + 1 = 6 : 3 x - 2 = 25 : 5 x + 2 = 560 : 7 ( 2x + 4 ) = 100 : 5
x + 1 = 2 x - 2 = 5 x + 2 = 80 ( 2x + 4 ) = 20
x = 2 - 1 x = 5 + 2 x = 80 - 2 2x = 20 - 4
x = 1 x = 7 x = 78 2x = 16
Vậy x = 1 Vậy x = 7 Vậy x = 78 => x = 8
vậy x = 8
tìm x thuộc n bieets
a, 20-(7 nhân (x-3)+4) =2
b, (7x-11)^3=25 nhân 5^2+200
a, 7*(x-3) + 4 = 18
<=> 7*(x+3) = 14
<=> x+3=2
<=> x= -1
b, ( 7x - 11)3 =825
<=> 7x - 11=\(\sqrt[3]{825}\)
<=> x=\(\frac{\sqrt[3]{825}+11}{7}\) (loại)