Algebra
posted by Algebra Parent on .
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

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) 
#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=y2y1/x2x1. The numbers 2&1 are below the y and x. Hehas used the formula y=mx+b before. 
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=y2y1/x2x1 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)