Annie tried to solve an equation step by step. 7.5 + k = 10 7.5 + k − 7.5 = 10 − 7.5 Step 1 k = 2.5 Step 2 7.5+k 7.5+k−7.5 k =10 =10−7.5 =2.5 Step 1 Step 2 Find Annie's mistake.

Step-by-step explanation:

Annie's mistake is in the second step.

He introduced "k7.5" & "-7.5k" which made him confuse and led him to delete "k", thereby omitting the variable being sort after

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

-8/2y-8=5/y+4-7y+8/y^2-16

we move all terms to the left:

-8/2y-8-(5/y+4-7y+8/y^2-16)=0

we can not solve this equation