\(4\times x^3+15=47\)
\(4\times x^3=32\)
\(x^3=8\)
\(x=2\)
toán lp 5 ak bn ? dễ quá ha --_--''
a) 4.x3+15=47
=> 4.x3=47-15
=> x3=32:4
=> x3=8
=> x3=23
=> x=2
b) 4.2x-3=125
=> 4.2x=125+3
=> 2x=128:4
=> 2x=32
=> 2x=25
=> x=5
a) \(4.x^3+15=47\)
\(4.x^3=47-15\)
\(4.x^3=32\)
\(x^3=8\)
=> x = 2
vậy x = 2
b) \(4.2^x-3=125\)
\(4.2^x=128\)
\(2^x=32\)
\(2^x=2^5\)
=> x = 5
vậy x=5