a.\(\dfrac{1}{4}+\dfrac{15}{16}:\dfrac{3}{8}x\dfrac{2}{3}=\dfrac{1}{4}+\dfrac{5}{2}x\dfrac{2}{3}=\dfrac{1}{4}+\dfrac{5}{3}=\dfrac{23}{12}\)
b.
+ Với a=58,47, ta có:
A=4,25.(58,47+41,53)-125=300
+Với A=53,3, ta có:
53,5 = 4,25.(a+41,53)-125 =>a=0,47
bài 1 :
a) \(\dfrac{1}{4}+\dfrac{15}{16}:\dfrac{3}{8}\cdot\dfrac{2}{3}=\dfrac{1}{4}+\dfrac{5}{2}\cdot\dfrac{2}{3}=\dfrac{1}{4}+\dfrac{10}{6}=\dfrac{6}{24}+\dfrac{40}{24}=\dfrac{23}{12}\)
b)A = 4,25 X ( 58,47 + 41,53 ) - 125 = 4,25 x 100 - 125 = 425 - 125 = 300
53,5 = 4,25 x ( a + 41,53 ) - 125
4,25 x ( a + 41,53 ) = 53,5 + 125
4,25 x ( a + 41,53 ) = 178,5
a + 41,53 = 178,5 : 4,25
a + 41,53 = 42
a = 42 - 41,53
a = 0,47