Respuesta :
Answer:
Year = 1995 and population = 315
Year = 2015 and population = 715
Step-by-step explanation:
It is given that the population of two different villages is modeled by the given equations:
[tex]y=x^2-30x+540[/tex]
[tex]y=20x+15[/tex]
The population of both villages are same after x years after 1980 if
[tex]x^2-30x+540=20x+15[/tex]
[tex]x^2-30x+540-20x-15=0[/tex]
[tex]x^2-50x+525=0[/tex]
Splitting the middle term, we get
[tex]x^2-15x-35x+525=0[/tex]
[tex]x(x-15)-35(x-15)=0[/tex]
[tex](x-15)(x-35)=0[/tex]
[tex]x=15,35[/tex]
It means, after 15 or 35 years, the population will same.
For x=15, years is [tex]1980+15=1995[/tex] and population is
[tex]y=20(15)+15=315[/tex]
For x=35, years is [tex]1980+35=2015[/tex] and population is
[tex]y=20(35)+15=715[/tex].
Therefore, population are equation in Year = 1995 and population = 315 or Year = 2015 and population = 715.
Year = 1995 and population = 315
Year = 2015 and population = 715
Calculation:
The equation is
[tex]y = x^2 - 30x + 540\\\\y = 20x + 15[/tex]
Now
[tex]x^2 - 30x + 540 = 20x + 15\\x^2 - 30x + 540 - 20x - 15=0\\\\x^2 - 50x + 525 = 0\\\\x^2 - 35x - 15x + 525=0\\\\x(x - 15) -35(x-15) = 0\\\\(x-15) (x-35) = 0[/tex]
x = 15,35
so,
When x is 15 , the population is = 20(15 ) +15 = 300 + 15 = 315
And, x is 35 , the population is = 20(35 ) +15 = 700 + 15 = 715
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