Hm

Step-by-step explanation:

Two fractions are said to be proportional to each when there exists a number such that

So k must be the same for both equations.

Let's analyze the 4 pairs of fractions:

1)

We have:

k is the same, so these two  fractions are proportional.

2)

We have:

k is NOT the same, so these two fractions are NOT proportional.

3)

We have:

k is NOT the same, so these two fractions are NOT proportional.

4)

We have:

k is NOT the same, so these two fractions are NOT proportional.

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places