How do you solve 42x=6?

1 Answer
Mar 28, 2016

You must use logarithms to solve.

Explanation:

If an=b, then logan=logb.

log42x=log6

Use the log rule logan=nloga to simplify further.

2xlog4=log6

x(log42)=log6

x=log6log16

x=0.65

Make sure to ask your teacher if they want your answer in exact form (x=log6log16) or rounded off to an x number of decimal points. I know that my teacher asks for two decimals after the point (x=0.65), but some ask for 1, 3 or 0.

Practice exercises:

  1. Solve for x:

a)23x2=17

b)34x+1=63x3

Challenge problem:

Solve for x in 22x3+5=33x

Hint: think of the log addition rule.

Good luck!