# graph problem

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• Jan 20th 2009, 08:52 PM
curlythornhill
graph problem
Sorry, new to this kind of thing. Just recieved assignments prior to starting a course and oh my gosh, its like rocket science to me having left school 20 years ago. These questions may seem simple to you, but they are as hard as the job i am currently doing overseas is to me. Please be gentle with me as the precious little brain i have is fragile. So here goes:-

Q1. Assume that you have plotted the graph of y = x^2 - 5x + 3 choose the option which corresponds to the additional line you would draw on your graph paper in order to solve graphically the equation x^2-5x=4.

Show all workings.

Q2. Assume that you have plotted the graph of y = x^2 - 7x + 8 choose the option which corresponds to the additional line you would draw on your graph paper in order to solve graphically the equation x^2 - 3x + 1 = 0.

Show all workings.

If anybody can help i would be very greatful.

curly
• Jan 20th 2009, 09:18 PM
Prove It
Quote:

Originally Posted by curlythornhill
Sorry, new to this kind of thing. Just recieved assignments prior to starting a course and oh my god, its like rocket science to me having left school 20 years ago. These questions may seem simple to you, but they are as hard as the job i am currently doing overseas is to me. Please be gentle with me as the precious little brain i have is fragile. So here goes:-

Q1. Assume that you have plotted the graph of y = x^2 - 5x + 3 choose the option which corresponds to the additional line you would draw on your graph paper in order to solve graphically the equation x^2-5x=4.

Show all workings.

Q2. Assume that you have plotted the graph of y = x^2 - 7x + 8 choose the option which corresponds to the additional line you would draw on your graph paper in order to solve graphically the equation x^2 - 3x + 1 = 0.

Show all workings.

If anybody can help i would be very greatful.

curly

For 1. If $x^2 - 5x = 4$ and $y = x^2 -5x + 3$ then $y = 4 + 3 = 7$ (can you see why?)

So the extra line you will draw is $y = 7$.

For 2. If $x^2 - 3x + 1 = 0$ and $y = x^2 - 7x + 8$, then

$y = x^2 - 3x + 1 - 4x + 7$ (can you see why?)

$y = 0 - 4x + 7$ (can you see why?)

$y = -4x + 7$.

So the extra line you draw is $y = -4x + 7$.