Question

Urgent ! Dau coroana !​

Answer 1

5)

7^x+1 + 7^x = 56

(7+1) * 7^x=56 => 8*7^x=56 => 7^x=7 => 7^x=7^1 =>x=1

6)

3^x+1 + 3^x+1 =4

(1+3) * 3^x+1 =4

4* 3^x+1=4 => 3^x+1=1 => 3^x+1 =3^0 => x+1=0 => x= -1

7)

2^x+1 + 2^x-3 = 2^x-4 + 33

(16+1) *2^x-3=2^x-4 + 33

17 * 2^x-3 = 2^x-4 +33

17*2^x-3-2^x-4=33

(17*2-1)*2^x-4=33

(34-1)*2^x-4=33

33*2^x-4=1

2^x-4=1

2^x-4=2^0

x-4=0 =>x=4

8)

2^x+4^x=20

2^x+(2^x)^2 = 20

a=2^x

a+a^2=20 => a=-5 , a=4

2^x= -5 , 2^x=4

x∉R , x=2

x=2 - aceasta e solutia

9)

3^x+9^x=3^2 * 10

3^x+(3^2)^x=3^2*10

a=3^x

a+a^2=3^2 * 10

a= - 10 , a=9

3^x= -10 , 3^x=9

x∉ R , x=2

x=2 - aceasta e solutia