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March 27, 2017

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Can someone tell me if these problems have the right answers? I am tooooooo old to know this any more. I understand the first one, but 2&3 are vaguely familiar.

25x^2+25x+6=0
the answer is x=-1/2 +/- 1/10

#2 solve for V=1/3Bh for B
answer is B=V/ 1/3h

#3 Find equation of line (-4,-3) and (5,6)
answer is 1x+y=-4

  • Algebra - ,

    the first one is wrong

    25x^2+25x+6=0 factors to
    (5x+2)(5x+3) = 0
    so x = -2/5 or x = -3/5

    in the second one
    V=1/3Bh multiply both sides by 3
    3V = Bh now divide both sides by h
    3V/h = B

    no for the third one, sorry 3 strikes!

    most students appear to be taught the
    y = mx + b method

    so slope = m = 9/9 = 1

    so y = x + b
    sub in one of the points, say (5,6)

    6 = 5 + b
    b = 1

    so the equation is y = x + 1 or
    x - y = -1

    (test the two given points, they both work. They don't work in your equation)

  • Algebra - ,

    #3 He has the m=9/9 slope

    the 6 and 5 are written m=6-(-3)/5-(-4), so he has a - sign where there should be a plus sign? He must be using the wrong formula, because at the beginning he has m=y2-y1/x2-x1. The numbers 2&1 are below the y and x. Hehas used the formula y=mx+b before.

  • Algebra - ,

    the slope is indeed 9/9 which is 1
    so m=1

    the calculations for slope are correct, I don't like the way you typed them.
    You have to use brackets to control the proper order of operation, so your

    m=6-(-3)/5-(-4) should be written as
    m=(6-(-3)) / (5-(-4))
    m = (6+3) / (5+4) because 6 - (-3) = 6 + (3)
    m = 9/9
    m =1

    m=y2-y1/x2-x1 is simply the formula used to find slope if you are given two points.
    it means take (the y of the second point - the y of the first point), then divide it by (the x of the second point - the x of the first point)

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