Tính giá trị biểu thức:
a) (33,7−31,5)+(57,6−55,4)(33,7−31,5)+(57,6−55,4)
b) (85,5+4,5)−(12,02+7,98)(85,5+4,5)−(12,02+7,98)
c) (15,25+3,75)×4+(20,71+5,29)×5(15,25+3,75)×4+(20,71+5,29)×5
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Bài 1:
câu a: 4\(\dfrac{4}{9}\) : 2\(\dfrac{2}{3}\) + 3\(\dfrac{1}{6}\)
= \(\dfrac{40}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{19}{6}\)
= \(\dfrac{5}{3}\) + \(\dfrac{19}{6}\)
= \(\dfrac{10}{6}\) + \(\dfrac{19}{6}\)
= \(\dfrac{29}{6}\)
b, (15,25 + 3,75) \(\times\) 4 + ( 20,71 + 5,29)\(\times\) 5
= 19 \(\times\) 4 + 26 \(\times\) 5
= 76 + 130
= 206
c, \(\dfrac{4}{5}\) \(\times\) \(\dfrac{1}{2}\) + \(\dfrac{4}{5}\) \(\times\) \(\dfrac{1}{3}\) - \(\dfrac{4}{5}\) \(\times\) \(\dfrac{1}{4}\)
= \(\dfrac{2}{5}\) + \(\dfrac{4}{15}\) - \(\dfrac{1}{5}\)
= \(\dfrac{6}{15}\) + \(\dfrac{4}{15}\) - \(\dfrac{3}{15}\)
= \(\dfrac{7}{15}\)
d, 1\(\dfrac{5}{7}\) + 7\(\dfrac{3}{6}\) + 2\(\dfrac{2}{7}\) - 4\(\dfrac{3}{6}\)
= (1 + 2 + \(\dfrac{5}{7}\) + \(\dfrac{2}{7}\)) + ( 7 + \(\dfrac{3}{6}\) - 4 - \(\dfrac{3}{6}\))
= 3 + 1 + 3
= 7
Ta có:
x − 4 , 5 = 7 , 98 x = 7 , 98 + 4 , 5 x = 12 , 48
Vậy x = 12 , 48
Đáp án D
a) 6,21 : 4,5 + 31,5 : 4,5 - 7,74 : 4,5
= (6,21 + 31,5 - 7,74) : 4,5
= 29,97 : 4,5
= 6,66
\(a,\left(-8,5\right)+16,35+\left(-4,5\right)-\left(-2,25\right)\\ =\left[\left(-8,5\right)+\left(-4,5\right)\right]+\left[16,35-\left(-2,25\right)\right]\\ =-13+18,6=5,6\\ b,5,63+\left(-2,75\right)-\left(-8,94\right)+9,06-15,25\\ =5,63-2,75+8,94+9,06-15,25\)
\(=5,63-\left(2,75+15,25\right)+\left(8,94+9,06\right)\\ =5,63-18+18\\ =5,63\)
a) (-8,5) + 16,35 + (-4,5) - (-2,25) = 5,6
b) 5,63 + (-2,75) - (-8,94) + 9,06 - 15,25 = 5,63
a x 3 + a x 3,5 + a x 4 + a x 4,5 = 31,5
a x ( 3 + 3,5 + 4 + 4,5 ) = 31,5
a x 15 = 31,5
==> a = 2,1 Tk mk,mk tk lại !!!!!
\(\Leftrightarrow\left|5-2x\right|=\dfrac{7,5+4,5}{4}=3\\ \Leftrightarrow\left[{}\begin{matrix}5-2x=3\\2x-5=3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=4\end{matrix}\right.\)
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