Tính
(x + 1)2 - 10(x + 1) + 25
Tính nhanh:
a) (1/2 : 50% - 1/4 : 25% + 1/8 : 12,5 - 1/10 : 10%) : 1 + 2 + 3 + ... 2006 + 2007 + 2008)
c) 8,1 : 0,6 x 1875 + 1,5 x 625 x 9
a: \(=\dfrac{\left(\dfrac{1}{2}:\dfrac{1}{2}-\dfrac{1}{4}:\dfrac{1}{4}+\dfrac{1}{8}:\dfrac{1}{8}-\dfrac{1}{10}:\dfrac{1}{10}\right)}{1+2+3+...+2008}\)
=0
c: =8,1*5/3*1875+13,5*625
=13,5(1875+625)
=13,5*2500
=33750
TÍNH NHANH
12 , 48 : 0, 5 x 6 , 25 x 4 x 2
-------------------------------------------
2 x 3 , 12 x 1 , 25 : 0 , 25 x 10
1. Tính : \(\dfrac{12}{4-\sqrt{10}}\)-6\(\sqrt{\dfrac{5}{2}}\)+\(\dfrac{5\sqrt{2}+\sqrt{10}}{\sqrt{5}+1}\)
2,Rút gọn:A=(\(\dfrac{\sqrt{x}}{\sqrt{x}-5}\)-\(\dfrac{5}{\sqrt{x}+5}\)+\(\dfrac{10\sqrt{x}}{25-x}\)):\(\dfrac{3}{\sqrt{x}+5}\)
1: \(=8+2\sqrt{10}-3\sqrt{10}+\sqrt{10}=8\)
tính nhanh
2 x 4 x 5 x 20 x 25 x 5
1 + 2 + 3 + .....+ 9 + 10
a) 2.4.5.20.25.5=(2.5).(4.25).(5.20)=10.100.100=100000
b) số số hạng (10-1):1+1=10
tổng là (10+1).10:2=55
2.4.5.20.25.5 = 100000
1+2+3+.....+9+10=55
1,Tính \(\dfrac{12}{4-\sqrt{10}}-6\sqrt{\dfrac{5}{2}}+\dfrac{5\sqrt{2}+\sqrt{10}}{\sqrt{5}+1}\)
2,Rút gọn:A=\(\left(\dfrac{\sqrt{x}}{\sqrt{x}-5}-\dfrac{5}{\sqrt{x}+5}+\dfrac{10\sqrt{x}}{25-x}\right):\dfrac{3}{\sqrt{x}+5}\)
1: \(=8+2\sqrt{10}-3\sqrt{10}+\sqrt{10}=8\)
Bài 1: Tìm x ,biết
1, 155 -10× (x+1) =55
2, 5×(x+12) +15 = 15 625 ÷425
3, 10 +12 +14 +... +98 -2x =100
Bài 2: Tính
1, 5 ×25 -18 ÷9
2, 17 ×85 +15 ×17 -120
3, 8 -125 ÷25 +12 ×4
bài 1
a) 155 - 10.(x+1) = 55
=>10 .(x+1) = 100
=>x + 1 = 10
=>x = 9
còn lại tương tự
Tính nhanh:
17/5*-31/125*1/2*10/17*-1/2^3
Tìm x :
a) x . ( x - 2 ) = 0
b) ( x - 1 ) . ( x - 3 ) = 2
Tính nhanh ( nếu có )
a) 15 . 37 .4 + 120 . 21 + 21 . 5 . 12
b) 19 + 19 . 99 - 25 . 8
c) 27 + 73 - 30 : ( 25 - 10 )
d) 15 - 25 . 8 : ( 25 - 10 )
\(x\left(x-2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x-2=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x=2\end{cases}}\)
bài 1: tính hợp lí
a) 5 x 72 x 10 x 2 b) 40 x 125 c) 4 x 2021 x 25 d) 16 x 6 x 25
bài 2: tính nhanh
a) 24 x 57 + 43 x 24 b) 12 x 19 + 80 x 12 +12
c) (36 x 15 x 169) : (5 x 18 x13) d) (44 x 52 x 60) : ( 11 x 13 x 15)
bài 3: tìm X
a) X - 280 : 35 = 5 x 54 b) ( X - 280) : 35 = 54 : 4
c) ( X - 128 + 20 ) : 192 = 0 d) 4 x ( X + 200) = 460 + 85 x 4
bài 4: thực hiện phép tính
a) 7/12 - 5/12 b) 8/11 + 19/11 c) 3/8 + 5/12 d) 3/4 + 7/12
bài 5: tìm x
a) X - 6/7 = 5/2 b) 12/7 : X + 2/3 = 7/5
Bài 1
a) \(5\times72\times10\times2=\left(5\times2\times10\right)\times72=100\times72=7200\)
b) \(40\times125=5\times\left(8\times125\right)=5\times1000=5000\)
c) \(16\times6\times25=4\times4\times6\times25=\left(4\times6\right)\times\left(4\times25\right)=24\times100=2400\) Bài 2:
a) \(24\times57+43\times24=24\times\left(57+43\right)=24\times100=2400\)
b) \(12\times19+80\times12+12=12\times\left(19+80+1\right)=12\times100=1200\)
c) \(\left(36\times15\times169\right)\div\left(5\times18\times13\right)\)
\(=\left(18\times2\times3\times5\times13\times13\right)\div\left(5\times18\times13\right)\)
\(=\left(2\times3\times13\right)\times\left(18\times5\times13\right)\div\left(5\times18\times13\right)\)
\(=2\times3\times13\)
\(=78\)
d) \(\left(44\times52\times60\right)\div\left(11\times13\times15\right)\)
\(=\left(4\times11\times4\times13\times4\times15\right)\div\left(11\times13\times15\right)\)
\(=\left(4\times4\times4\right)\times\left(11\times13\times15\right)\div\left(11\times13\times15\right)\)
\(=4\times4\times4\)
\(=64\)
Bài 3:
a) \(x-280\div35=5\times54\)
\(x-8=270\)
\(x=270+8\)
\(x=278\)
b) \(\left(x-280\right)\div35=54\div4\)
\(\left(x-280\right)\div35=\dfrac{27}{2}\)
\(x-280=\dfrac{27}{2}\times35\)
\(x-280=\dfrac{945}{2}\)
\(x=\dfrac{945}{2}+280\)
\(x=\dfrac{1505}{2}\)
c) \(\left(x-128+20\right)\div192=0\)
\(x-128+20=0\times192\)
\(x-128+20=0\)
\(x-128=0-20\)
\(x-128=-20\)
\(x=-20+128\)
\(x=108\)
d) \(4\times\left(x+200\right)=460+85\times4\)
\(4\times\left(x+200\right)=460+340\)
\(4\times\left(x+200\right)=800\)
\(x+200=800\div4\)
\(x+200=200\)
\(x=200-200\)
\(x=0\)
Bài 4:
a) \(\dfrac{7}{12}-\dfrac{5}{12}=\dfrac{2}{12}=\dfrac{1}{6}\)
b) \(\dfrac{8}{11}+\dfrac{19}{11}=\dfrac{27}{11}\)
c) \(\dfrac{3}{8}+\dfrac{5}{12}=\dfrac{9}{24}+\dfrac{10}{24}=\dfrac{19}{24}\)
d) \(\dfrac{3}{4}+\dfrac{7}{12}=\dfrac{9}{12}+\dfrac{7}{12}=\dfrac{16}{12}=\dfrac{4}{3}\)
Bài 5:
a) \(x-\dfrac{6}{7}=\dfrac{5}{2}\)
\(x=\dfrac{5}{2}+\dfrac{6}{7}\)
\(x=\dfrac{47}{14}\)
b) \(\dfrac{12}{7}\div x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\dfrac{12}{7}\div x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\dfrac{12}{7}\div x=\dfrac{11}{15}\)
\(x=\dfrac{12}{7}\div\dfrac{11}{15}\)
\(x=\dfrac{180}{77}\)
\(1.\)Tính bằng cách thuận tiện
10 x 45 - 25 x 10
100 x 2 + 100 x 3
10 x 45 - 25 x 10
= 10 x ( 45 - 25 )
= 10 x 20
= 200
100 x 2 + 100 x 3
= 100 x ( 2 + 3 )
= 100 x 5
= 500
10 x 45 - 25 x 10
= 10 x [45 - 25]
= 10 x 20
= 200
100 x 2 + 100 x 3
= 100 x [2 + 3]
= 100 x 5
= 500
\(10.45-25.10=10\left(45-25\right)=10.20=200\)
\(100.2+100.3=100.\left(2+3\right)=100.5=500\)