if this function f(x) has x-intercepts at x=7 and x= -2 and a y- intercept at y=5, how would i know how to solve this?
Please show me step by step, i want to learn not just the answer. Thank you
Determine this quadratic function. Please help!?
2015-08-31 9:19 am
回答 (2)
2015-08-31 9:46 am
x-intercepts at x = 7 and x = -2.
Hence, f(7) = 0 and f(-2) = 0
(x - 7) and (x + 2) are the factors of f(x).
Let f(x) = y = a(x - 7)(x + 2)
y-intercept at y = 5.
Hence, f(0) = 5
a(0 - 7)(0 + 2) = 5
a = -5/14
Then, f(x) = -(5/14)(x - 7)(x + 2)
or f(x) = -(5/14)x² + (25/14)x + 5
Hence, f(7) = 0 and f(-2) = 0
(x - 7) and (x + 2) are the factors of f(x).
Let f(x) = y = a(x - 7)(x + 2)
y-intercept at y = 5.
Hence, f(0) = 5
a(0 - 7)(0 + 2) = 5
a = -5/14
Then, f(x) = -(5/14)(x - 7)(x + 2)
or f(x) = -(5/14)x² + (25/14)x + 5
2015-08-31 10:05 am
Intercepts at x=7 and x=-2 means factors (x-7) and (x+2).
So f(x)=c(x-7)(x+2), for some constant c.
The y intercept is the value of f(x) where x=0, which is where the curve meets the y-axis. So sub x=0 and equate to 5.
-14c=5 so c=-5/14 so
f(x)=(-5/14)(x-7)(x+2)
So f(x)=c(x-7)(x+2), for some constant c.
The y intercept is the value of f(x) where x=0, which is where the curve meets the y-axis. So sub x=0 and equate to 5.
-14c=5 so c=-5/14 so
f(x)=(-5/14)(x-7)(x+2)
收錄日期: 2021-04-18 00:09:38
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20150831011933AAPUjMg