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(12 + 77 + 34 + 23 + 88 + 45 + 55 + 66) x (45200 – 1808 x 25)
=(12 + 77 + 34 + 23 + 88 + 45 + 55 + 66) x (45200-45200)
=(12 + 77 + 34 + 23 + 88 + 45 + 55 + 66) x 0
=0
35 . 34 + 35 . 38 + 65 . 75 + 65 . 45 + 35 . 34 =
= 35 . 34 + 35 . 38 + 35 . 34 + 65 . 75 + 65 . 45
= 35 . ( 34 + 38 + 34 ) + 65 . ( 75 + 45 )
= 35 . 110 + 65 . 110
= 110 . ( 35 + 65 )
= 110 . 100
= 11000
Hok tốt!!!!!!!!!!!!!
a) Tính bằng cách hợp lí nhất :
35 . 34 + 35 . 38 + 65 . 75 + 65 . 45 + 35 . 34
= 35 . 34 + 35 . 38 + 35 . 34 + 65 . 75 + 65 . 45
= 35 . ( 34 + 38 + 34 ) + 65 . ( 75 + 45 )
= 35 . 106 + 65 . 120
= 3710 + 7800
= 11510
3 . 25 . 8 + 4 . 37 . 6 + 2 . 38 . 12
= 3 . 8 . 25 + 4 . 6 . 37 + 2 . 12 . 38
= 24 . 25 + 24 . 37 + 24 . 38
= 24 . ( 25 + 37 + 38 )
= 24 . 100
= 2400
b) Tìm số tự nhiên x, biết :
( x - 5 ) ( x + 7 ) = 0
\(\Rightarrow\orbr{\begin{cases}x-5=0\\x+7=0\end{cases}\Rightarrow\orbr{\begin{cases}x=5\\x=-7\end{cases}}}.\)
Vậy .......
(900-45)x45+(800+55)x55
=855x45+855x55
=855x(45+55)
=855x100
=85500
= 25 x 75/100 + 75 x 0.92 + 25 x 0.25 + 75 x 8/100
= 25 x 0.75 + 75 x 0.92 + 25 x 0.25 + 75 x 0.08
= 25 x ( 0.75 + 0.25 ) + 75 x ( 0.92 + 0.08 )
= 25 x 1 + 75 x 1
= ( 25 + 75 ) x 1
= 100 x 1
= 100
Giải:
( 12 + 77 + 34 + 23 + 88 + 45 + 55 + 66 ) . ( 45200 - 1808 .25 )
=( 12 + 77 + 34 + 23 + 88 + 45 + 55 + 66 ) . ( 45200 - 45200 )
=( 12 + 77 + 34 + 23 + 88 + 45 + 55 + 66 ) . 0
=0
Học tốt!!!
(12+77+34+23+88+45+55+66)* (45200-1808*25)
=(12+77+34+23+88+45+55+66)* (45200-45200)
=(12+17+34+23+88+45+55+66)* 0
=0
a) 652 + 327 + 148 + 73 = ( 652 + 148) +( 327+73) = 800+400 =1200
b) 19 x 16 x 4 + 76 x 34 = ( 19 x 4 ) x 16 + 76 x 34 = 76 x 16 + 76 x 34 = 76 x( 16+34 ) = 76 x 50= 3800
c) 136 x 68 + 16 x 2 x 136 = 136 x ( 68 + 32 ) = 136 x 100 = 13600
d) 45 x 125 - 45 x 25 + 55 x 31 + 55 x 69 = 46 x ( 125-25) + 55 x ( 31+69) = 46 x100 + 55x 100 = 4600 + 5500 = 10100
e) 125 x 25 + 125 x 74 + 125 = 125 x( 25+74 +1 ) = 125 x 100 =12500
f) 43,5 x 2015 x ( 630 - 315 x 2 ) = 43,5 x 2015 x 0 = 0
g) 0,2 x 41 x 36 + 0,8 x 9 x 58 + 1,2 x 6
= 0,2 x4 x41x 9 + 0,8 x 9 x 58 +7,2
= (0,8 x9)x 41 + ( 0,8 x 9) x 58 + 7,2 x 1
= 7,2 x 41 + 7,2 x 58 + 7,2 x 1
= 7,2 x( 41+58+1)
= 7,2 x 100 = 720.
a) 652 + 327 + 148 + 73
=(73+327)+(652+148)
=400+800
=1200
b) 19 x 16 x 4 + 76 x 34
=76*16+76*34
=76*(16+34)
=76*50
=3800
c)136*68+16*2*136
=136*68+32*136
=136*(68+32)
=136*100
=13600
d)45*125-45*25+55*31+55*69
=45*(125-25)+55*(31+69)
=45*100+55*100
=100*(45+55)
=100*100
=10 000
e)125*25+125*74+125
=125*(25+75+1)
=125*100
=12 500
còn lại bạn tự làm đi mk mỏi tay lắm rồi
\(\dfrac{45.21.25}{7.15.36}=\dfrac{3.3.3.5.7.5.5}{7.5.3.3.2.3.2}=\dfrac{25}{4}\)
45\7 x 21\15 x 25/36
=45x21x25/7x15x36
=15x3x7x3x25/7x15x3x12
=3x25/12
=75/12
=25/4
\(=\left[66+34+77+23+12+88+45+55\right]\times\left[1808\times\left(25-25\right)\right]\\ =0\)
\(0,25+25\%\times55+\dfrac{1}{4}\times45-\dfrac{2}{8}\)
\(=\dfrac{1}{4}+\dfrac{1}{4}\times55+\dfrac{1}{4}\times45-\dfrac{1}{4}\)
\(=\dfrac{1}{4}\times\left(1+55+45-1\right)\)
\(=\dfrac{1}{4}\times100\)
\(=25\)
\(0,25+25\%\times55+\dfrac{1}{4}\times45-\dfrac{2}{8}\)
\(=\dfrac{1}{4}+\dfrac{1}{4}\times55+\dfrac{1}{4}\times45-\dfrac{1}{4}\)
\(=\dfrac{1}{4}\times1+\dfrac{1}{4}\times55+\dfrac{1}{4}\times45-\dfrac{1}{4}\times1\)
\(=\dfrac{1}{4}+\left(1+55+45-1\right)\)
\(=\dfrac{1}{4}\times100\)
\(=0,25\times100\)
\(=25\)
\(#:)\)