The figure shows the graph y = -2x2. Points A and B are on the graph. AB is parallel to the x-

This topic has expert replies
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

[GMAT math practice question]

The figure shows the graph y = -2x^2. Points A and B are on the graph. AB is parallel to the x-axis, and the length of AB is 8. What is the area of OAB?
5.29ps.png
A. 110
B. 118
C. 128
D. 138
E. 140
Source: — Problem Solving |

User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members
=>

Assume A(-p, -2p^2) and B(p, -2p^2) on the graph.

The length of AB, 2p is 8 and we have 2p = 8 or p = 4.
The area of the triangle is (1/2)AB·height = (1/2)(2p)(2p^2) = 2p^3 = 2·4^3 = 128.

Therefore, C is the answer.
Answer: C