Rhianna is baking a cake and some cookies for a party. She used cups of flour for the cake. For each tray of cookies, she needs cups of flour. She decides to use at least 15 cups of flour for the cake and the cookies. Assuming she can make fractional trays of cookies, how many trays, x, can she make? Select the inequality that includes the minimum number of trays of cookies Rhianna can make.

answer: x=3 and y=4

step-by-step explanation:

9x

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