(a) Find x given that [tex]4^x=2[/tex]
(b) Let x = 1.1609... be the positive real number such that [tex]4^x=5[/tex]. Prove that x is irrational.

Respuesta :

Answers:

(a) x = 0.5

(b) Given Below.

Explanation:

(a)

[tex]4^x = 2[/tex]

apply ln both sides

[tex]ln(4^x) = ln(2)[/tex]

simplify

[tex]xln(4) = ln(2)[/tex]

divide both sides by ln(4)

[tex]x = 0.5[/tex]

(b)

Recall that rational numbers can be expressed in fractions a/b

[tex]4^x = 5[/tex]

apply ln on both sides

[tex]ln( 4^x) = ln(5)[/tex]

simplify

[tex]xln( 4) = ln(5)[/tex]

divide both sides by ln(4)

[tex]x =\frac{ ln(5)}{ln(4)}[/tex]

simplify

[tex]x =1.160964047...[/tex]  The value is endless and continues.

The following cannot be expressed as a fraction or whole number.

Hence, the following value of x is irrational.