Question

(4x + 5 ) : 3 - 121 : 11 = 4

1 + 3 + 5 + ... + x = 1600 (x la mot so tu nhien le)

2^x + 2^x+3 =144

( x - 5)⁴ = ( x - 5)⁶

Answer 1

(4x+5):3-121:11=4

(4x+5):3-11=4

(4x+5):3=15

4x+5=45

4x=40

x=10.

1+3+5+...+x=1600

Gọi x=2k+1

Ta có 1+3+...+x=1600

1+3+..+2k+1=1600

(2k+2)[(2k+1-1)/2+1]/2=1600

(2k+2)(k+1)=3200

2(k+1)(k+1)=3200

(k+1)^2=1600

=>k+1=40

k=39. Vậy x=2k+1=2.39+1=79.

2^x+2^x+3=144

2^x(1+2^3)=144

2^x.9=144

2^x=16

2^x=2^4

=>x=4

(x-5)^4=(x-5)^6

(x-5)^6-(x-5)^4=0

(x-5)^4[(x-5)^2-1]=0

(x-5)^4=0, (x-5)^2-1=0

x-5=0, (x-5)^2=1

x=5, x-5=1, x-5=-1

x=5, x=6, x=4.

 

Answer 2

(4x+5):3-121:11=4