Alberta Free Tutoring And Homework Help For Math 20-1

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The system 3x-y+4=0 and x2-8y-1=0 will have

a. o solutions

b. 1 real solution

c. 2 real solutions

d. an infinte number of real solutions

7 years ago

Answered By Jesslyn C

We first want to isolate the y variable in each equation so we can see what types of functions we are dealing with. 

 

3x-y+4 =0 ->  y=3x+4

x^2 - 8y - 1 =0 -> y = 1/8 x^2 - 1/8

now we know we have a positive linear function and a quadratic with a minimum vertex and y intercept at -1/8. 

There are a few ways to solve this:

1. Graph the 2 functions to see how many intersection points there are. 

A. If you graph both we can see there are 2 intersection points and therefore 2 Real solutions. 

2. Since the question is asking about the number of solutions and not the actual solution we need to combine the functions and find the discriminate (d=b^2 - 4ac).

 

3x+4 = 1/8 x^2 -1/8

8(3x+4) = x^2 - 1

24x + 32 = x^2 - 1 

0 = x^2 - 24x - 33

 

d= (-24)^2 - 4(1)(-33) =  708

since it is a positive value we know there are 2 Real solutions.