Respuesta :
Answer:
Step-by-step explanation:
The zeros of this cubing function are easily read from the graph: {-20, -5, 15}.
The factors of this polynomial are therefore (x + 20), (x + 5) and (x - 15).
The y-intercept is (0, 1).
The function is thus f(x) = a(x + 20)(x + 5)(x - 15).
According to the y-intercept, if x = 0, y = 1.
Thus, y = 1 = f(0) = a(20)(5)(-15), or 1 = a(100)(-15), or 1 = -1500a.
Then a = -1/1500, and the function is:
f(x) = (-1/1500)(x^3 + .. + .. + ... ). We must multiply out (x + 20)(x + 5)(x - 15) to obtain f(x) in finished form.
Answer:
zeros: (-20, 0), (-5, 0) and (15, 0)
factors: (x + 20), (x + 5) and (x - 15)
f(x) = a*(x + 20)*(x + 5)*(x - 15)
a = -1/1500
f(x) = -1/1500*(x + 20)*(x + 5)*(x - 15)
f(x) = -1/1500*x^3 - 1/100*x^2 + 11/60x + 1
Step-by-step explanation:
The zeros of the function are those points where the function intercepts the x-axis. They are: (-20, 0), (-5, 0) and (15, 0)
The zeros of a polynomial are expressed as factors as follows: (x - a) where a is a zero. Then, for this case, the factors are (x + 20), (x + 5) and (x - 15)
The equation of f(x) use the factors and the leading coefficient as follows: f(x) = a*(x + 20)*(x + 5)*(x - 15)
Applying the distributive property of multiplication, we get the expanded form:
f(x) = a*(x + 20)*(x + 5)*(x - 15)
(x + 20)*(x + 5) = x^2 + 5x + 20x + 20*5 = x^2 + 25x + 100
f(x) = a*(x^2 + 25x + 100)*(x - 15)
(x^2 + 25x + 100)*(x - 15) = x^3 - 15x^2 + 25x^2 - 15*25x + 100x - 100*15 = x^3 + 15x^2 - 275x - 1500
f(x) = a*(x^3 + 15x^2 - 275x - 1500)
The y-intercept of the graph is (0, 1). Replacing this point into the function equation:
1 = a*(0 + 20)*(0 + 5)*(0 - 15)
1 = a*20*5*(-15)
1 = a*(-1500)
a = -1/1500
Replacing this value into the function equation:
f(x) = (-1/1500)*(x^3 + 15x^2 - 275x - 1500)
f(x) = -1/1500*x^3 - 1/100*x^2 + 11/60x + 1