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algebra ll

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Which choice is the equation of a line that passes through the point (5, –1) and is perpendicular to the line represented by this equation?

y = −x + 5

A. y = x− 6

B. 5x − y = 5

C. y = −x− 1

D. 2x− 5y = −1


  • algebra ll -

    just to give you a head's up... i'm refreshing my memory on slope and graphing and I plan on getting back to you as soon as I figure this problem out. Give me a hour or so. So far it looks like you will need to do an inverse of slope intercept or something to that effect. Will return with an answer shortly, please bear with me.

  • algebra ll -

    ok so it is quite simple. The answer is A. y=x-6. Let me show you how it is simple. You need to know a couple of formulas. y = mx + b is the formula for a line. Where m = slope (rise over run, or simply y over x since y is rise 'veritcal rise up and down' and x is run 'horizontal run'). b is referred to as the y-intercept this is always the point on the y axis at which the line intercects this axis. Also know this formula is the point-slope formula. This is the formula that we will be use to find the perpindicular line. It is: (y-y subscript 1) = m(x-x subscript 1). The little 1 (subscripted) is just the two points that are given in the equation which are (5,-1). So you will plug this information into the formulas and this will give you what you want to find as far as the formula goes. But before you do that here is the trick. For a perpindicular line you simple invert the slope of the line formula given in the problem and you will have a perpindicular line slope. for example in our problem there is an understood 1 in front of the x and it is negative so the slope is -1 for our line in the equation. To get the perpindicular line you will invert that to positive 1. That's it. If it were a fraction you would invert it, for example if the m given in the equation was 2/3 the perpindicular line of that slope is the inverse so -3/2 would be the perpindicular lines slope. Back to the problem. Plug in our points into the point slope formula and put in the inverted m (positive 1) i just discussed gives us this (y-(-1)) = 1(x-5). So now solve this so that y is alone = y+1 = x-5 which further becomes y = x-6 which is answer A in the choice list. I hope you understand how it comes out. Let me know if you have problems.

  • algebra ll -

    9y2+4=12y how to solve this equation using the zero factor

  • algebra ll -

    Erica please elaborate on what you are explaining here with the zero factor formula you have laid out? It isn't exactly self explanatory.

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