ogneshelle

27.04.2021 • 

Mathematics

Mr. Johnson is also comparing the two mobile phone data plans. Talk First charges $20 plus $5 per GB of data, while Mobile Plus charges $30 plus $3 per GB of data. At what amount of GB use will the cost of the two data plans be the same? Mr. Johnson wrote this equation for the scenario. 1. d = amount of data used (GB)

2. Talk First = Mobile Plus

3. 20d + 5 = 30d + 3

Analyze Mr. Johnson’s work and identify his mistake.

In step 1, his variable should be c, representing company.
In step 2, his translated equation should be Talk First + Mobile Plus = Total
Money.
In step 3, he multiplied the variable by the base monthly cost instead of by the
cost per GB.

Ответ:

muravyevaarina

25.09.2022

Mathematics

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Hello here is a solution :

x²+6x+8 = x² +6x+(9-1)
              = (x²+6x +9) -1 
              =( x² +2(3)(x) +3² )-1 
by identite : a²+2ab+b² = (a+b)²
x²+6x+8 = (x+3)² -1²
by identite : a²-b² = (a-b)(a+b)

x²+6x+8 = (x+3+1)(x+3-1) 
x²+6x+8 = (x+4)(x+2)

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