Graphing Linear Equations: Solving x2+4x-7=0 with Hints

[chikis]

Hello folks, here is a problem. I don't know how and where to start solving it:
A student is told to draw a linear graph on the same axis such that the intersection of the two graph will give the solutions to the equation x2+ 4x -7 =0. What is the equation of the linear graph he needs to draw?
A. x=1 B. x=-1 C. y=1 D. y=-1 E. x+y=1
I don't know where to start from. Can anyone help? Just give me hints that I will follow in proceeding towards the calculation. Please note that I mean x squared when I wrote x2. Thank you.

 

[tiny-tim]

hello chikis!

A student is told to draw a linear graph on the same axis such that the intersection of the two graph …

but what's the first graph?

 

[chikis]

hello chikis!


but what's the first graph?

The first graph is a quadratic graph (y=x2+4x-6).

 

[tiny-tim]

The first graph is a quadratic graph (y=x2+4x-6).

ok, so you need to combine y = x² + 4x - 6 with x² + 4x - 7 = 0

 

[chikis]

ok, so you need to combine y = x² + 4x - 6 with x² + 4x - 7 = 0

You mean I should combine them by adding it up together as in y= (x2+4x-6) + (x2+4x-7)=0. Is that what you mean?

 

[tiny-tim]

no, i mean combine them as in simultaneous equations

('cos you want them to be simultaneously true )

 

[chikis]

no, i mean combine them as in simultaneous equations

('cos you want them to be simultaneously true )

You mean I should arrange and solve them like this like if am solving simultanous equation?:
y=x2+4x-6
x2+4x-7=0.
Is that what you mean?

 

[tiny-tim]

yes!

 

[chikis]

yes!

That cannot be true because all the two equation resembles quadratic equation. In that case it (the both equation) cannot be solved simultanously. For that to be possible it means that one of the equation has to be linear and the other quadratic.

 

[tiny-tim]

That cannot be true because all the two equation resembles quadratic equation. In that case it (the both equation) cannot be solved simultanously.

no, the second equation isn't y = x² + 4x - 7

 

[chikis]

no, the second equation isn't y = x² + 4x - 7

does that look like linear equation to you?

 

[tiny-tim]

You mean I should arrange and solve them like this like if am solving simultanous equation?:
y=x2+4x-6
x2+4x-7=0.

just solve them!

 

[chikis]

just solve them!

That cannot be possible. It can't work that way. Maybe you should try it; let's see what you will get. How about that?