X * 9 - (3 * X + 28) = 176
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1/2 x 2/8 x 3/28 x 4/77 x 5/176
\(=\frac{1.2.3.4.5}{2.8.28.77.176}=\frac{1.2.3.4.5}{2.2.4.7.4.11.4.4}=\frac{3.5}{2.7.4.4.11.4}=\frac{15}{9856}\)
210 - 18 : ( 370 : x - 2 ) - 28 = 176
210 - 18 : ( 370 : x - 2 ) = 176 + 28 = 204
18 : ( 370 : x - 2 ) = 210 - 204 = 6
370 : x - 2 = 18 : 6 = 3
370 : x = 3 + 2 = 5
x = 370 : 5 = 74
Giải:
\(\dfrac{3}{2}+\dfrac{6}{8}+\dfrac{9}{28}+\dfrac{12}{77}+\dfrac{15}{176}\)
\(=\dfrac{3}{1.2}+\dfrac{6}{2.4}+\dfrac{9}{4.7}+\dfrac{12}{7.11}+\dfrac{15}{11.16}\)
\(=3.\left(\dfrac{1}{1.2}+\dfrac{2}{2.4}+\dfrac{3}{4.7}+\dfrac{4}{7.11}+\dfrac{5}{11.16}\right)\)
\(=3.\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}\right)\)
\(=3.\left(1-\dfrac{1}{16}\right)\)
\(=3.\dfrac{15}{16}\)
\(=\dfrac{45}{16}\)
Đặt A = \(\dfrac{3}{2}+\dfrac{6}{8}+\dfrac{9}{28}+\dfrac{12}{77}+\dfrac{15}{176}\)
= \(3\left(\dfrac{1}{1\times2}+\dfrac{2}{2\times4}+\dfrac{3}{4\times7}+\dfrac{4}{7\times11}+\dfrac{5}{11\times16}\right)\)
= \(3\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}\right)\)
= \(3\left(1-\dfrac{1}{16}\right)=3\times\dfrac{15}{16}=\dfrac{45}{16}\)
a) 4 756+9xX=8 788 b)X-176-242=357
9xX=8 788-4 756 X-176 =357+242
9xX=4 032 X-176 =599
X=4 032:9 X =599+176
X=448 X =775
C)X:2:3=150 D)Xx6+160=196
X:2 =150x3 Xx6 =196-160
X:2 =450 Xx6 =36
X 450x2 X =36:6
X =900 X =6
K CHO TÔI NHA
\(176:x^2+79=10\cdot9\)
\(\Leftrightarrow176:x^2=11\)
\(\Leftrightarrow x=4\)
X * 9 - (3 * X + 28) = 176
\(x.9-x.3=176+28\)
\(6x=204\)
\(x=204:6\)
\(x=34\)
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