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Giai
Hieu cua hai so bang \(\frac{1}{4}\) so be, vay so be chiem 4 phan, hieu chiem 1 phan
So lon chiem so phan la:
1 + 4 = 5 (phan)
So be la:
15,3 : (4 + 5) x 4 = 6,8
So lon la:
15,3 : (4 + 5) x 5 = 8,5
Dap so: So be: 6,8
So lon: 8,5
b, (y+1) + (y+2) + (y+3) + .... + (y+99) = 6138
(y+y+y+y+....+y) + (1+2+3+...+99) = 6138
99.y + 4950 = 6138
99.y = 6138 - 4950
99.y = 1188
y = 1188 : 99
x = 12
a) \(\left(y+1\right)+\left(y+4\right)+\left(y+7\right)+....+\left(y+28\right)=155155\)
\(\Rightarrow\left(y+y+...+y\right)+\left(1+4+7+...+28\right)=155155\)
\(\Rightarrow10x+145=155155\)
\(\Rightarrow10x=155010\)
\(\Rightarrow x=15501\)
Vậy x = 15501
b) \(\left(y+1\right)+\left(y+2\right)+..+\left(y+99\right)=6138\)
\(\Rightarrow\left(y+y+...+y\right)+\left(1+2+3+...+99\right)=6138\)
\(\Rightarrow99x+4950=6138\)
\(\Rightarrow99x=1188\)
\(\Rightarrow x=12\)
Vậy x = 12
Đáy nhỏ hình thang: 24:3x2= 16(cm)
Chiều cao hình thang: 30 x 2 : 5 = 12(cm)
Diện tích hình thang ban đầu: (24 + 16) x 12 : 2 = 240 (cm2)
Đ.số: 240cm2
3y + 1/2y + 1/4y = \(1\frac{1}{2}\)
15/4y = \(1\frac{1}{2}\)
y = \(1\frac{1}{2}:\frac{15}{4}=\frac{3}{2}:\frac{15}{4}=\frac{2}{5}\)
Trả lời:
\(y\times\frac{15}{2}-\frac{1}{3}\times\left(\frac{1}{4}+y\right)=96\frac{2}{3}\)
\(\Leftrightarrow y\times\frac{15}{2}-\frac{1}{12}-\frac{1}{3}\times y=\frac{290}{3}\)
\(\Leftrightarrow y\times\left(\frac{15}{2}-\frac{1}{3}\right)=\frac{387}{4}\)
\(\Leftrightarrow y\times\frac{43}{6}=\frac{387}{4}\)
\(\Leftrightarrow y=\frac{27}{2}\)
Vậy \(y=\frac{27}{2}\)
\(\left(y-\frac{1}{2}\right):\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{90}\right)=\frac{1}{3}\)
=> \(\left(y-\frac{1}{2}\right):\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}\right)=\frac{1}{3}\)
=> \(\left(y-\frac{1}{2}\right):\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{9}-\frac{1}{10}\right)=\frac{1}{3}\)
=> \(\left(y-\frac{1}{2}\right):\left(1-\frac{1}{10}\right)=\frac{1}{3}\)
=> \(\left(y-\frac{1}{2}\right):\frac{9}{10}=\frac{1}{3}\)
=> \(y-\frac{1}{2}=\frac{3}{10}\)
=> \(y=\frac{13}{10}\)
Study well ! >_<
\(2,35:\left(y-15,3\right)=\dfrac{1}{2}\)
\(y-15,3=2,35:\dfrac{1}{2}\)
\(y-15,3=4,7\)
\(y=4,7+15,3\)
\(y=20\)
\(2,35:\left(y-15,3\right)=\dfrac{1}{2}\)
\(y-15,3=2,35:\dfrac{1}{2}\)
\(y-15,3=4,7\)
\(y=4,7+15,3\)
\(y=20\)