k3ateanaKatnBn k3ateanaKatnBn

21-11-2016
Mathematics

contestada

If x+y=15 and x-y=25, then what is the value of 2x^2 - y^2?
A) 425
B) 775
C) 825
D) 1,575
E) 1,625 ...?

Respuesta :

mozarth11 mozarth11

21-11-2016

x+y = 15
x-y = 25
------------
2x = 40
x = 40/2
x = 20

y = 15-x
y = 15-20
y = -5

2x² - y² =
2*20² - (-5)² =
2*400 - 25 =
800 - 25 =
775

Answer Link

rybag99 rybag99

21-11-2016

The answer is B as since x = 20 and y = -5

Answer Link

Otras preguntas

Determine the number of significant figures in each measurement 508.0 l

The expression 5/9 (F – 32) shows how to convert from degrees Fahrenheit to degrees Celsius, where F represents the temperature in degrees Fahrenheit. What is t

What you prefer compass and straightedge vs drawing programs. Why??

What is the solution to this system

Finish pattern 444, 4400, 44,400

An investor seeking tax advantages through an oil and gas dpp. with this type of partnership he would expect to benefit most from

How do you find the equation for the line that is parallel to the line y=2/3x-7 and passes through the point (3,-1)

A ball is projected upward at time t = 0.0 s from a point on a roof 90 m above the ground. The ball rises, then falls and strikes the ground. The initial veloc

Which following statement would roger williams agree with1. the doctrine of persecution for the cause of conscience is justified by the bible 2. all religions w

What is the value of X?