Question

X=y²-1

2x - y = 4
Which of the following equations could be the result of using substitution to solve the system?
2y²-y-5=0
2y2-y-6=0
2y2-2y-5=0

Answer 1

• x=y²-1

Put in second

• 2x-y=4
• 2(y²-1)-y=4
• 2y²-2-y=4
• 2y²-y-6=0

Answer 2

B) 2y² - y - 6 = 0

Given following:

• x = y² - 1 ___equation 1

• 2x - y = 4 ___equation 2

Insert equation 1 into 2:

• 2(y² - 1) - y = 4

• 2y² - 2 - y = 4

• 2y² - y - 2 - 4 = 0

• 2y² - y - 6 = 0