|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
04 Jul 2023, 03:45
Kudos
Bookmarks
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
72% (02:22) correct
28%
(03:03)
wrong
based on 312
sessions
History
Date
Time
Result
Not Attempted Yet
If function f(x) = (x - a)(x - b) and f(10) = f(20) = 0, what is the value of f(30) ?
A. 50
B. 100
C. 150
D. 200
E. 250
A. 50
B. 100
C. 150
D. 200
E. 250
04 Jul 2023, 03:53
Kudos
Bookmarks
Since f(10) = f(20) = 0, a and b must be 10 and 20 (not necessarily in that order).
So f(x) = (x-10)(x-20)
f(30) = 20*10 = 200
Option D is answer.
So f(x) = (x-10)(x-20)
f(30) = 20*10 = 200
Option D is answer.
Bunuel
04 Jul 2023, 04:05
Kudos
Bookmarks
If function f(x) = (x - a)(x - b) and f(10) = f(20) = 0, what is the value of f(30) ?
A. 50
B. 100
C. 150
D. 200
E. 250
f(x) = (x - a)(x - b)
f(10) = (10 - a)(10 - b) = 100 - 10(a+b) + ab = 0 ------------ a)
f(20) = (20 - a)(20 - b) = 400 - 20(a+b) + ab = 0 ------------ b)
f(30) = (30 - a)(30 - b) = 900 - 30(a+b) + ab ------------ c)
from a,b
30(a+b) = 500 + 2ab ------------ d)
substitute d in c
900 - 500 - 2ab + ab => 400 - ab ------------e)
Now 2*a - b
200 - 20(a+b) + 2ab - 400 + 20(a+b) -ab = -200 + ab = 0
so ab = 200------------------f)
substitute f in e.
400 - 200 = f(30) = 200
A. 50
B. 100
C. 150
D. 200
E. 250
f(x) = (x - a)(x - b)
f(10) = (10 - a)(10 - b) = 100 - 10(a+b) + ab = 0 ------------ a)
f(20) = (20 - a)(20 - b) = 400 - 20(a+b) + ab = 0 ------------ b)
f(30) = (30 - a)(30 - b) = 900 - 30(a+b) + ab ------------ c)
from a,b
30(a+b) = 500 + 2ab ------------ d)
substitute d in c
900 - 500 - 2ab + ab => 400 - ab ------------e)
Now 2*a - b
200 - 20(a+b) + 2ab - 400 + 20(a+b) -ab = -200 + ab = 0
so ab = 200------------------f)
substitute f in e.
400 - 200 = f(30) = 200
