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Câu 1:
a: x+2,57=14,25-6,3
=>x+2,57=7,95
=>x=5,38
b: 12,9-x=4,2+2,4
=>12,9-x=6,6
hay x=6,3
a) \(18+25\times4-4^3\)
\(=18+100-64\)
\(=118-64\)
\(=54\)
b) \(275-\left(49+125\div5^3\right)\)
\(=275-\left(49+125\div125\right)\)
\(=275-\left(49+1\right)\)
\(=275-49-1\)
\(=226-1\)
\(=225\)
c) \(2015+\left(8\times15-\left(18-8\right)^2\right)\)
\(=2015+\left(8\times15-\left(10\right)^2\right)\)
\(=2015+\left(8\times15-100\right)\)
\(=2015+\left(120-100\right)\)
\(=2015+20\)
\(=2035\)
a, 165:11.999 + 85.999 = (15.11):11.999 + 85.999 = [(15.11):11].999 + 85.999
= 15.(11:11).999 + 85.999 = 15.999 + 85.999 = (15+85).999 = 99900
b, 25.4 + 25:5 – 4.(30 – 5) – 5 = 25.4 + 25:5 – 4.25 – 5 = (25.4 – 4.25) + (25:5 – 5) = 0 + 0 = 0
a) \(4.3^4-16:2^2+2.5^3\)
\(=4.81-16:4+2.125\)
\(=324-4+250\)
\(=570\)
b) \(100:\left\{250:\left[450-\left(4.5^3-25.4\right)\right]\right\}\)
\(=100:\left\{250:\left[450-\left(500-100\right)\right]\right\}\)
\(=100:\left\{250:\left[450-400\right]\right\}\)
\(=100:\left\{250:50\right\}\)
\(=100:5\)
\(=20\)
nhớ là 3 k nhá
a) 4.3^4-16:2^2+2.5^3
= 4.81-16:4+2.125
= 324-4+250
= 320+250
= 570
b)100:{250:[450-(4.5^3-25.4)]}
= 100:{250:[450-(4.125-100)]}
= 100:{250:[450-(500-100)]}
= 100:{250:[450-400]}
= 100:{250:50}
= 100:5
= 20
nhớ đúng cho mình nha
Bài 2:
a: \(\left(6x-39\right):7=3\)
\(\Leftrightarrow6x-39=21\)
hay x=10
`(3x+1)^2=25.4`
<=> `(3x+1)^2=10^2`
<=> `3x+1=10` hoặc `3x+1=-10`
<=> `x=3` hoặc `x=-11/3`