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9 votes
(a) Find x given that
4^x=2

(b) Let x = 1.1609... be the positive real number such that
4^x=5. Prove that x is irrational.

1 Answer

10 votes

Answers:

(a) x = 0.5

(b) Given Below.

Step-by-step explanation:

(a)


4^x = 2

apply ln both sides


ln(4^x) = ln(2)

simplify


xln(4) = ln(2)

divide both sides by ln(4)


x = 0.5

(b)

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


4^x = 5

apply ln on both sides


ln( 4^x) = ln(5)

simplify


xln( 4) = ln(5)

divide both sides by ln(4)


x =( ln(5))/(ln(4))

simplify


x =1.160964047... 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.

User Jgroenen
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