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4 * 3 * 25 *125 * 8
=(4*25) * (125 *8) * 3
= 100 * 1000 * 3
= 300 000
a)
(x*211)+(1+2+...+211)=23632
(x*211)+22366=23632
x*211=23632-22366
x*211=1266
x=1266:211
x=6
Vậy x=6
\(\frac{5+8+11+14+...+68+71}{2\times43+3\times43+43\times5+7}\).
Xét tử số: 5+ 8+ 11+ 14+...+ 68.
Có số các số hạng là:
( 68- 5): 3+ 1= 22
Tử số là:
( 68+ 5)x 22: 2= 803
Xét mẫu số: 2x 43+ 3x 43+ 43x 5+ 7=( 2+ 3+ 5)x 43+ 7= 10x 43+ 7= 430+ 7= 437.
=> \(\frac{5+8+11+14+...+68+71}{2\times43+3\times43+43\times5+7}\)= \(\frac{803}{437}\).
`#3107`
`7/13 \div x = 14/39`
`=> x = 7/13 \div 14/39`
`=> x = 3/2`
Vậy, `x = 3/2`
________
`x \times 3/5 = 14/15`
`=> x = 14/15 \div 3/5`
`=> x = 14/9`
Vậy, `x=14/9.`
\(\dfrac{7}{13}:x=\dfrac{14}{39}\)
\(x=\dfrac{7}{13}:\dfrac{14}{39}\)
\(x=\dfrac{7}{13}\times\dfrac{39}{14}\)
\(x=\dfrac{3}{2}\)
___
\(x\times\dfrac{3}{5}=\dfrac{14}{15}\)
\(x=\dfrac{14}{15}:\dfrac{3}{5}\)
\(x=\dfrac{14}{15}\times\dfrac{5}{3}\)
\(x=\dfrac{14}{9}\)
14 phút = 7/30 giờ
24 giờ = 1 ngày
71 giờ = 4260 phút
Giải:
\(9-3\times\left(x-9\right)=6\)
\(3\times\left(x-9\right)=9-6\)
\(3\times\left(x-9\right)=3\)
\(x-9=3:3\)
\(x-9=1\)
\(x=1+9\)
\(x=10\)
\(4+6\times\left(x+1\right)=70\)
\(6\times\left(x+1\right)=70-4\)
\(6\times\left(x+1\right)=66\)
\(x+1=66:6\)
\(x+1=11\)
\(x=11-1\)
\(x=10\)
\(\dfrac{x}{13}+\dfrac{15}{26}=\dfrac{46}{52}\)
\(\dfrac{x}{13}=\dfrac{23}{26}-\dfrac{15}{26}\)
\(\dfrac{x}{13}=\dfrac{4}{13}\)
\(\Rightarrow x=4\)
\(\dfrac{11}{14}-\dfrac{3}{x}=\dfrac{5}{14}\)
\(\dfrac{3}{x}=\dfrac{11}{14}-\dfrac{5}{14}\)
\(\dfrac{3}{x}=\dfrac{3}{7}\)
\(\Rightarrow x=7\)
\(5\times\left(3+7\times x\right)=40\)
\(3+7\times x=40:5\)
\(3+7\times x=8\)
\(7\times x=8-3\)
\(7\times x=5\)
\(x=5:7\)
\(x=\dfrac{5}{7}\)
\(x\times6+12:3=120\)
\(x\times6+4=120\)
\(x\times6=120-4\)
\(x\times6=116\)
\(x=116:6\)
\(x=\dfrac{58}{3}\)
\(x\times3,7+x\times6,3=120\)
\(x\times\left(3,7+6,3\right)=120\)
\(x\times10=120\)
\(x=120:10\)
\(x=12\)
\(\left(15\times24-x\right):0,25=100:\dfrac{1}{4}\)
\(\left(360-x\right):0,25=400\)
\(360-x=400.0,25\)
\(360-x=100\)
\(x=360-100\)
\(x=260\)
\(71+65\times4=\dfrac{x+140}{x}+260\)
\(\left(x+140\right):x+260=71+260\)
\(x:x+140:x+260=331\)
\(1+140:x+260=331\)
\(140:x=331-1-260\)
\(140:x=70\)
\(x=140:70\)
\(x=2\)
\(\left(x+1\right)+\left(x+4\right)+\left(x+7\right)+...+\left(x+28\right)=155\)
\(10\times x+\left(1+4+7+...+28\right)=155\)
Số số hạng \(\left(1+4+7+...+28\right)\) :
\(\left(28-1\right):3+1=10\)
Tổng dãy \(\left(1+4+7+...+28\right)\) :
\(\left(1+28\right).10:2=145\)
\(\Rightarrow10\times x+145=155\)
\(10\times x=155-145\)
\(10\times x=10\)
\(x=10:10\)
\(x=1\)
Đều theo cách lớp 5 nha em!
\(\dfrac{70}{39}\times\dfrac{13}{14}-\dfrac{13}{25}:\dfrac{39}{50}=\dfrac{5}{3}-\dfrac{13}{25}\times\dfrac{50}{39}=\dfrac{5}{3}-\dfrac{2}{3}=1\)
\(\dfrac{70}{39}\cdot\dfrac{13}{14}-\dfrac{13}{25}:\dfrac{39}{50}\)
\(=\dfrac{5}{3}-\dfrac{13}{25}\cdot\dfrac{50}{39}\)
\(=\dfrac{5}{3}-\dfrac{2}{3}\)
=1
\(\dfrac{7}{13}\times\dfrac{5}{14}\times\dfrac{39}{15}=\dfrac{7\times5\times3\times13}{13\times7\times2\times5\times3}=\dfrac{1}{2}\)
\(\dfrac{7}{13}\cdot\dfrac{5}{14}\cdot\dfrac{39}{15}=\dfrac{1}{2}\)
68
\(125:\left(39-14\right)+14-142:71\\ =125:25+14-2\\ =5+14-2\\ =17\)