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\(0,25\times1,25\times8\times40+3,5\times67+3,5\times31+7\times1\)
\(=\left(0,25\times40\right)\times\left(1,25\times8\right)+3,5\times\left(67+31\right)+7\)
\(=10\times10+3,5\times98+7\)
\(=100+343+7\)
\(=450\)
Tính bằng cách thuận tiện nhất :
a. 67 x 126 - 67 x 84 - 41 x 67 - 67
= 67 x 126 - 67 x 84 - 41 x 67 - 67 x 1
= 67 ( 126 - 84 - 41 - 1 )
= 67 x 0
=0
b. 36 x 2 x 2 + 7 x 28
= 2 ( 36 x 2 + 14 x 7 )
= 2 x 170
= 340
c. 24 x 18 + 12 x 64
= 12 x 2 x 18 + 12 x 64
= 12 ( 2 x 18 + 64)
= 12 x 100
= 1200
a. 67 x 126 - 67 x 84 - 41 x 67 - 67
= 67 x 126 - 67 x 84 - 41 x 67 - 67 x 1
= 67 ( 126 - 84 - 41 - 1 )
= 67 x 0
=0
b. 36 x 2 x 2 + 7 x 28
= 2 ( 36 x 2 + 14 x 7 )
= 2 x 170
= 340
c. 24 x 18 + 12 x 64
= 12 x 2 x 18 + 12 x 64
= 12 ( 2 x 18 + 64)
= 12 x 100
= 1200
40,67x4+40,67x5+40,67
= 40,67x(4+5+1)
= 40,67x 10
= 406,7
Các câu sau làm tương tự
nhaXuân Sáng_Clever_2005
40,67 x 4 + 40,67 x 5 + 40,67
= 40,67 x 4 + 40,67 x 5 + 40,67 x 1
= 40,67 x ( 4 + 5 + 1 )
= 40,67 x 10
= 406,7
99 x 7 + 99 x 2 + 99
= 99 x 7 + 99 x 2 + 99 x 1
= 99 x ( 7 + 2 + 1 )
= 99 x 10
= 990
67 x 13 + 67 x 7 + 67
= 67 x 13 + 67 x 7 + 67 x 1
= 67 x ( 13 + 7 + 1 )
= 67 x 21
= 1407
Ai tích mình, mình tích lại! Hứa luôn!
`@` `\text {Ans}`
`\downarrow`
`a,`
`(x-1954) \times 5=50`
`x-1954 = 50 \div 5`
`x-1954 = 10`
`x=10 + 1954`
`x= 1964`
`B.`
`48 - 40 \times x=8`
`40 \times x=48-8`
`40 \times x = 40`
` x=40 \div 40`
`x=1`
`C.`
`2+70 \div x = 3`
`70 \div x = 3-2`
`70 \div x = 1`
`x=70 \div 1`
`x=70`
`D. [3 \times (x+2) \div 7] \times 4=120`
`3 \times (x+2) \div 7 = 120 \div 4`
`3 \times (x+2) \div 7 =30`
`3 \times (x+2) = 30 \times 7`
`3 \times (x+2)=210`
`x+2=210 \div 3`
`x+2=70`
`x=70-2`
`x=68`
`E.`
`7,2 \div [ (0,6 \times x+8) \div 20 + 59] = 0,12?` Thiếu ngoặc bạn nhé._.
\(a,\left(x-1954\right)\times5=50\\ x-1954=50:5\\ x-1954=10\\ x=1954+10\\ x=1964\\b.48-40\times x=8\\40\times x=48-8\\40\times x=40\\ x=40:40\\ x=1 \\ c.2+70:X=3\\ 70:x=3-2\\ 70:x=1\\ x=70:1\\ x=70\\ d,\left[3\times\left(x+2\right):7\right]\times4=120\\ 3\times\left(x+2\right):7-120:4\\ 3\times\left(x+2\right):7=30\\ \left(x+2\right):7=30:3\\ \left(x+2\right):7=10\\ x+2=10\times7\\ x+2=70\\ x=70-2\\ x=68\)
A = 2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
= 24 x 53 + 24 x 87 - 24 x 40
= 24 x ( 53 + 87 - 40 )
= 24 x 100
= 2400
B = 5 x 7 x 77 - 7 x 60 + 49 x 25 - 15 x 42
= 5 x 7 x 77 - 7 x 5 x 12 + 49 x 5 x 5 - 5 x 3 x 42
= 5 x 539 - 84 x 5 + 245 x 5 - 5 x 126
= 5 x ( 539 - 84 + 245 - 126 )
= 5 x 574
= 2870
a=2×53×12+4×6×87-3×8×40
a=24×53+24×87-24×40
a=24×(53+87-40)
a=24×100
a=2400
a) \(\frac{8}{x}=\frac{40}{45}=\frac{8}{9}\)
=> 8 . 9 = x . 8
<=> x = 9
b) \(\frac{2}{5}+\frac{x}{7}=\frac{5}{6}\)
\(\Leftrightarrow\frac{x}{7}=\frac{5}{6}-\frac{2}{5}=\frac{13}{30}\)
\(\Leftrightarrow x=\frac{13}{30}.7=\frac{91}{30}\)
\(\frac{39}{40}-\frac{7}{9}\div\frac{2}{3}\left(\times\frac{3}{2}\right)\times\frac{2}{7}\)\(=\frac{39}{40}-\frac{7\times3\times2}{3\times3\times2\times7}=\frac{39}{40}-\frac{1}{3}\)\(=\frac{117}{120}-\frac{40}{120}=\frac{77}{120}\)
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\(\frac{20}{63}\div\frac{8}{9}\left(\times\frac{9}{8}\right)+\frac{5}{6}\times\frac{51}{70}=\frac{5\times4\times9}{9\times7\times4\times2}+\frac{5\times17\times3}{3\times2\times5\times14}\)\(=\frac{5}{14}+\frac{17}{28}=\frac{10+17}{28}=\frac{28}{28}=1\)
a. (45-63+18) x (1+2+3+4+5+6+7+8+9)
= 0 x (1+2+3+4+5+6+7+8+9) = 0
b. 60-61+62-63+64-65+66-67+68-69+70
= 60 + (-61-69)+(62+68)+(-63-67)+(64+66)-65+70
= 60 + (-130)+130+(-130)+130-65-70
= 60 + (-130+130) + (-130+130)-65+70
= 60 - 65 + 70 = 65
67 - 7 x (2+x) + 8 = 40
60 x (2+x) + 8 = 40
(2+x) +8 = 60: 40
(2+x) +8 = 20
2+x = 12
x = 12-2
x =10
đề sai hay sao ý