Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 decade ago

Algebra point slope help?

I have posted SO many questions about this part of math, and no matter what, I CAN'T understand it! Please help.

Find the point that lies on the line described by the equation below.

y - 5 = 6(x - 7)

A. (7, -5)

B. (5, 7)

C. (42, 5)

D. (7, 5)

Please and thanks :]

3 Answers

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  • 1 decade ago
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    Point slope formula is just y - (y1) = m (x - (x1)) where y1 and x1 are coordinates of a point on the line and m is the slope.

    y - y1 = m(x - x1)

    y - 5 = 6(x - 7)

    From just that, you can see that y1 = 5 and x1 = 7, which gives the coordinates (7, 5).

    But if you're stuck on that, you can move the 5 over and get rid of the parentheses. Then you'll get the formula in common form, y = 6x - 37.

    If you substitute in the x-values given in the answers, you can find the y-values that will correspond. Starting with A, if x = 7, y = 5, so A isn't the answer, but D is right.

    y = 6(7) - 37

    y = 42 - 37

    y = 5

    The coordinates are (7, 5)

  • 1 decade ago

    The answer is D.

    To find the answer, you should know the point slope formula.

    y - k = m(x - h)

    In this version of the equation, (h, k) is the point. so you just find h and k in the original problem, and take them and plug it in. In this case, h = 7 and k = 5, so the answer is (7, 5).

    Just make sure that both h and k are subtracted, because if they are added that means they are really negative numbers. for example:

    y - 5 = 6(x + 7)

    If this was the case, it doesn't look the like original point slope formula, because it has an addition sign in it. So, make it a subtraction sign:

    y - 5 = 6(x - ( -7) )

    Which means h = 5, and k = -7, so the point would be (5, -7).

    I hope this helps!

  • 1 decade ago

    Point-slope form is as follows

    y - h = m(x - g), where m is the slope of the line and the point (g,h) is on the line.

    So for yours g = 7 and h = 5 so the point is (7,5)

    The problem with the occurs when something like this comes up.

    y + 3 = x - 2

    For this you have to create the form by remembering that minus a negative is plus and that when there is nothing there it is understood to be 1. so by rewriting you get.

    y - (-3) = 1(x-2)

    So your slope is 1 and the point would be (2, -3)

    I just made that up.

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