For a long-distance person-to-person telephone call, a telephone company charges $ 0.21 for the first minute, $ 0.17 for each additional minute, and a $ 1.59 service charge. if the cost of a call is $ 2.31 comma how long did the person talk?

4 minutes

Step-by-step explanation:

0.21+1.59=1.8

2.31=0.17x+1.8

Subtract 1.8 from both sides

0.51=0.17x

Divide both sides by 0.17

3=x

3 minutes plus the original minute spent talking

They spent 4 minutes total talking on the phone

i found two solutions,   n = 2 • ± √3 = ± 3.4641

step-by-step explanation:

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