Question

Tìm x

a) 197 -9 ( x+3) =80

b) 7 (x- 14) + 35 = 56

c) 2.3^x+1 =54

d) 3.2^x-1 =24

Answer 1

a)197-9(x+3)=80

=>9(x+3)=197-80

=>9(x+3)=117

=>x+3=117:9

=>x+3=13

=>x=13-3=10

b)7(x-14)+35=56

=>7(x+14)=56-35

=>7(x+14)=21

=>x+14=21/7

=>x+14=3

=>x=3-14=(-11)

c)2.3^x-1=54

=>3^x-1=54:2

=>3^x-1=27

=>3^x-1=3³

=>x-1=3

=>x=3+1=4

d)3.2^x-1=24

^=>2^x-1=24:3

=>2^x-1=8

=>2^x-1=2³

=>x-1=3

=>x=3+1=4

 

Answer 2

\(a,197-9\left(x+3\right)=80\)

\(197-\left(9x+27\right)=80\)

\(197-9x-27=80\)

\(197-9x=107\)

\(9x=90\)

\(x=10\)

\(b,7\left(x-141\right)+35=56\)

\(7x-987+35=56\)

\(7x=56-35+987\)

\(7x=1008\)

\(x=144\)

Answer 3

197 - 9 . ( x + 3 ) = 80 

          9 . ( x + 3 ) = 197 - 80 

          9 . ( x + 3 ) = 117

                 x + 3    = 117 : 9 

                 x + 3    = 13

                 x           = 13 - 3 

                 x           = 10 

7 . ( x - 14 ) + 35 = 56 

7 . ( x - 14 )          = 56 - 35 

7 . ( x - 14 )          = 21 

        x - 14            =  21 : 7 

        x - 14            = 3 

        x                    = 3 + 14 

        x                    = 17 

Answer 4

\(a,197-9.\left(x+3\right)=80\)

\(9.\left(x+3\right)=197-80\)

\(9.\left(x+3\right)=117\)

          \(x+3=117:9\)

           \(x+3=13\)

                     \(x=13-3\)

                     \(x=10\)

\(b,7.\left(x-14\right)+35=56\)

\(7.\left(x-14\right)=56-35\)

\(7.\left(x-14\right)=21\)

\(x-14=21:7\)

\(x-14=3\)

\(x=3+14\)

\(x=17\)

Answer 5

a,10

b,17

Answer 6

\(c,2.3^{x+1}=54\)

\(3^{x+1}=54:2\)

\(3^{x+1}=27\)

\(3^{x+1}=3^3\)

\(\Rightarrow x+1=3\)

\(\Rightarrow x=3-1\)

\(\Rightarrow x=2\)

\(d,3.2^{x-1}=24\)

\(2^{x-1}=24:3\)

\(2^{x-1}=8\)

\(2^{x-1}=2^3\)

\(x-1=3\)

\(x=4\)