15 POINTS which could be the first step in sloving the equation 2.5x + 1.2 = 1.2x + 4.2

A. add 4.2 to each side

B. divide both sides by 1.2x

C. add 2.5x to each side

D. subtract 1.2 from both sides

D. subtract 1.2 from both sides

Step-by-step explanation:

It is the subtraction property of equality.

a

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