Question

Tìm x 

4x³ + 12 = 120

3.2^x - 3 = 45

Answer 1

Tìm x, biết:

a) 4x³+12=120

=>4x³=120-12

=>4x³=108

=>x³=108:4

=>x³=27

=>x³=3³

=>x=3

b) 3.2^x-3=45

=>3.(2^x-1)=45

=>2^x-1=45:3

=>2^x-1=15

=>2^x=15+1

=>2^x=16

=>2^x=2⁴

=>x=4

Answer 2

4x^3+12=120

4x^3      =120-12

4x^3       =108

x^3          =108:4

x^3           =27

x^3           =3^3

\(\Rightarrow\)x=3

3.2^x-3=45

3.2^x=45+3

3.2^x=48

2^x=48:3

2^x=16

2^x=2^4

\(\Rightarrow\)x=4

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