Thread: Solving a y=x^2 graph

1. Solving a y=x^2 graph

Hi I have answered some questions and was hoping to find out if I have answered them correctly.

Questions

a) Plot on graph paper the graph of y=x^2 for values of x between -8 and +8

Use the graph to solve the following equations

b) X^2 = 7x + 2

c) X^2 = 4 – 6x

d) Verify your solutions numerically

Answers

Solution to a), b) and c)

plot x^2 = 7x + 2

http://www.wolframalpha.com/input/?i=plot+%28y%3Dx^2%29%2C+%28x^2%3D7x%2B2%29+-8+to+8

and x^2 = 4-6x against y=x^2

http://www.wolframalpha.com/input/?i=plot+%28y%3Dx^2%29%2C+%28x^2%3D4-6x%29+-8+to+8

d) Use the quadratic formula to solve numerically

x^2 = 7x + 2 becomes: x^2-7x-2=0

x = -0.274197, 7.24792

x^2 = 4-6x becomes: x^2+6x-4=0

x= -6.6055551, 0.60555127

Would simply plotting b) and c) against x^2 be the answer to those questions?

Thanks for any help.

2. Re: Solving a y=x^2 graph

In my opinion you didn't answer questions a),b) and c), wolphram alpha did, but I think you understand what to do.

3. Re: Solving a y=x^2 graph

lol, it was the easiest way to put a graph up. So simply plotting all 3 graphs against each other would answer the first 3 questions? Sorry, if it is the case I'm just in a little disbelief over it.

4. Re: Solving a y=x^2 graph

Yes, in my opinion the first question is a little bit strange, you have to use both graphs to solve it graphically, if you want to determine $x^2=7x+2$ then plot the graphs $y=x^2$ and $y=7x+2$ and look where they have intersection points.

Thank you!