A)
y=2^x
4^x=2^(2x)=y²
solution:
y=2^x hence y²=4^x
chek:
x=5 ⇒ y=2⁵=32
4⁵=1024
y₂=32²=1024
b)
8(4^x)-9(2^x)+1=0
8(2^(2x)-9(2^x)+1=0
2^x=t
8t²-9t+1=0
We solve the quadratic.
t₁=1/8 ⇒2^x=1/8
2^x=1/2³
2^x=2⁻³
x=-3
t₂=1 ⇒ 2^x=1 ⇒x=0
Solutions:
x=-3
x=0
Multiplication and division with the powers of ten
So, when multiply powers of ten, all you have to do add up the powers.
The reverse goes when you are dividing. You would subtract the powers.
9 x 10^7 => 3 x 10^3
The words " how many times as large as " indicates that we are going to divide the two, making it look like this:

Divide the 9 by 3 you get 3
Then subtract 10^3 from 10^7
Therefore, the answer is 3 x 10^4, or A
Check the picture below.
as you recall from the previous exercise, x = 74°, now, using the "inscribed angle theorem" as you saw already, the green intercepted arc is 160°, so y = 160° - 74°.
as far as ∡z, well, we can just use the "inscribed quadrilateral conjecture".
Any number that can be rewritten as a simple fraction is a rational number. This means that natural numbers, whole numbers and integers, like 5, are all part of the set of rational numbers as well because they can be written as fractions, as are mixed numbers like 1