Monday
December 5, 2016

Posts by Steve

Total # Posts: 46,840

Differential calculus
Since the distance from the vertex to the directrix is 4, then the standard parabola x^2 = 4py has p=4. So, with the translation of the vertex to (3,-4), and the directrix above the vertex, the parabola opens downward, so the equation is (x-3)^2 = -16(y+4) confirmed at http://...
November 8, 2016

Algebra
well, x = 5y-19 use that in 7x-2y=32
November 8, 2016

math
2x^-5 = 2/x^5 2x^(-3/4) = 2/x^(3/4) a negative exponent just means shifting the value between numerator and denominator. Note that this also means that 2/x^(-2) = 2x^2 since that is 2 / (1/x^2) = 2 * x^2/1 = 2x^2
November 8, 2016

Calculus
Just substitute 6 for 1.8 in your time function. You will find that the shortest time is to boat all the way. A little analysis will show you that if the boat is faster than the running, the boat is the best way. If the ratio of the boat:run speed is k, then the distance ...
November 8, 2016

science
depends how far it slides. Just note the change in PE: mgh
November 8, 2016

Math
suppose that you allow 0/0 = x for some value x. Then, clearing fractions, 0 = 0*x But that is true for any value x. That is why 0/0 is not defined.
November 8, 2016

Geometry
Looks good.
November 8, 2016

geometry
see your other postings under different names.
November 8, 2016

math geometry
Mixing up problems, aren't you? Anyway, C's x-value is 3/7 of the way from 2 to 16. And try using the same name for all your postings.
November 8, 2016

geometry
X is 2/7 of the way from M to N. So, X's y-value will be 2/7 of the distance from 3 to 10. ...
November 8, 2016

Math
Note that the dog years grow by 4 for every increase of 1 human year. So, using the hint, so that at x=2, (x-2)=0, y = 4(x-2)+23
November 8, 2016

Geometry (Please check my work)
M->M', so the scale is 2/6, not 6/2
November 8, 2016

Oral Literature = Oxymoron!
!!
November 8, 2016

Calculas-Differentiation
I'll help you with the calculus: y'(x) = x-4 The rest is just Algebra I.
November 8, 2016

math
a+b+c
November 8, 2016

math
clearly its area is ?(x-1)^2 m^2
November 8, 2016

Calculus
If the cuts are length x, then the volume is v = (24-2x)(45-2x)(x) = 4x^3 - 138x^2 + 1080x dv/dx = 12x^2 - 276x + 1080 = 12(x^2-23x+90) = 12(x-18)(x-5) You can take it from there ...
November 8, 2016

math
how many in each pack
November 8, 2016

Basic Calculus
2(width+length)=240 width+length = 120 width = 120-length area = length*width = length*(120-length)
November 8, 2016

dynmic
a = s" = 4 F = ma
November 8, 2016

algebra
what? reposting after 11 minutes? What a waste of time for all.
November 8, 2016

algebra
you change the direction of the inequality when multiplying by negative values. This is just a shorthand way of moving terms from one side to the other: -2/5x - 9 < 9/10 -9 < 9/10 + 2/5x -9 - 9/10 < 2/5 x -9.9 < 2/5 x -9.9 * 5/2 < x -24.75 < x This is the ...
November 8, 2016

math
just use your formulas! ar^2 = (a + ar)/2 2r^2 = 1+r (2r+1)(r-1) = 0 Now you have r and a, and S = a/(1-r)
November 8, 2016

time speed and distance
A went 210 km in 3.5 hr (11:30) A stopped till 11:58 A then went on. So, A's position x in terms of time elapsed from 8:00 is x = 60t for 0 <= t <= 7/2 210 for 3.5 <= t <= 3 29/30 210+60(t-3 29/30) for t > 3 29/30 A reached Q at 11:58+0:55 = 12:53 B's ...
November 7, 2016

calculus
Did you draw the lines? You have a rectangle and a trapezoid. Surely you can handle that. Or, you can think of the figure as a small triangle and a large triangle.
November 7, 2016

Calculus
there are many Riemann Sum calculators online. google is your friend
November 7, 2016

geometry
You want E to be 3/4 of the way from C to D. So, for both x and y, you want to go 3/4 of the distance from C to D. The x-coordinates differ by 8 The y-coordinates differ by 4 So, you want to add (6,3) to C, making E=(1,2)+(6,3)=(7,5)
November 7, 2016

Algrebra, Graphs, Math
The equation represents a line. Two points determine a line. The easiest two points to find on the line are the axis intercepts. When x=0, y=3 When y=0, x=3 So, plot the points (0,3) and (3,0) and draw a line through them.
November 7, 2016

precalc
area of a sector is a = 1/2 r^2 ? so, the area is 1/2 ?(123/180) (24^2-3^2) = 608.6 in^2
November 7, 2016

pre-calculus
Po e^(20k) = 900 Po e^(30k) = 1600 e^(10k) = 16/9 k = 0.019 And you can take it from there, I assume.
November 7, 2016

Math
(1+r/100)^r = 1/9 no real solutions. Let's try simple interest: (r/100)*r = 1/9 r^2 = 100/9 r=10/3 = 3.33%
November 7, 2016

math last question asap ples :P
B: 5-12-13 is a right triangle since 5^2 + 12^2 = 13^2
November 7, 2016

pre-calc.
also, this is just the change of base formula, so ln(100)/ln(10) = log10100 = 2
November 7, 2016

math
41÷3 is a single value. Nothing can be "between" it Now, if you want two quotients with 41÷3 between them, then surely you can use 40÷3 and 42÷3 I think you need to review the problem and fix your posting.
November 7, 2016

calculus
Just use the power rule and the chain rule. y = u^n dy/dx = n u^(n-1) du/dx Now just plug in your u=2x+2 and crank it out. I might even go ahead and simplify it to y = 2^3 (x+1)^3 = 8(x+1)^3 Then du/dx = 1
November 7, 2016

Math
3 + 6*4 + 3 or 3 + 6*(4+3) the language is ambiguous
November 7, 2016

Calculus
Well, come on - is it Precal or calculus? Answer - It's Algebra 2. And stop reposting right away under a new topic, ok? What a waste of time. |a+bi| = ?(a^2+b^2)
November 7, 2016

algebra 2
That's "perform" I'll assume you know how to add and multiply polynomials for A-D. f(g) = 5g^3-2g = 5(3x^3)^3-2(3x^3) = 135x^9-6x^3 g(f) = 3f^3 = 3(5x^3-2x)^3 = 375x^9-450x^7+180x^5-24x^3
November 7, 2016

geometry
If the length is x, then 2*4*5 + 2*5x + 2*4x = 166 Now just solve for x
November 7, 2016

Pre-Calculus
Recall that |a+bi| = ?(a^2+b^2)
November 7, 2016

Math 062
The proportion is bogus x = 25*50 which is meaningless. You need either gal/gal = tanks/tanks 50/25 = x/1 x = # tanks needed or gal/tank = gal/tank 50/x = 25/1 x = # tanks needed
November 7, 2016

maths help steve&reiny
I guess the math gets a bit tricky, but just note that 97 = 81+16
November 7, 2016

Vectors
ships sail on headings, not bearings. A bearing is the direction of an object from your position. (It may also be your heading, if you are going directly there.) So, can you at least convert those times and speeds to distance vectors? Add them all up x-y wise and figure the ...
November 7, 2016

calculus
Ok, we've done a bunch of these for you. What ideas do you have? I'll get you started with f'(x) = -sin(x) cos(cos(x)) e^sin(cos(x)) The rest is just algebra and trig.
November 7, 2016

pre algebra
just shift the decimal point 5 places to the left.
November 7, 2016

calculus
the line has slope 2. So, a perpendicular to the line will have slope -1/2, which will be the slope of the radius. A line through (0,0) with slope -1/2 is y = -1/2 x. This line intersects the circle at (-2/?10 , 1/?10). Now just find the distance between that point and the ...
November 7, 2016

calculus
y = x^3+2x^2+bx y' = 3x^2+4x+b y'(1) = 3+4+b = 7+b y(1) = 1+2+b = 3+b So the line through (1,3+b) with slope 7+b is y-(3+b) = (7+b)(x-1) y = (7+b)x - 4 y=0 at x = 4/(7+b) So, under what condition will the tangent line(s) not intersect the x-axis? See an example for b...
November 7, 2016

Calculas @Reiny
Hey - everyone needs a hobby ...
November 7, 2016

math
Hmmm. Since there are 21 terms in the expansion, the 11th term is the middle one. Adjust the numbers accordingly.
November 7, 2016

Pre-Algebra
huh? Huh??? y = x/4 when x=40, y = 40/4 Stop guessing and start calculating...
November 7, 2016

Pre-Algebra
3 = 12/4 y=x/4, so ...
November 7, 2016

Physics
1% = 1/100 sheesh!
November 7, 2016

Physics
what, you've forgotten your algebra? Multiply by 100nto lear the fractions: R/n = nR/100 100R = n^2R 100 = n^2
November 7, 2016

Physics
If each resistor has value R, then R/n = nR/100 100 = n^2 n=10
November 7, 2016

Calculas
well, there is a horizontal asymptote at y = -3/4
November 7, 2016

Calculus
looks good. f(x) has a min when f' changes from - to + (f bottoms out and starts back up) That happens at x=2pi
November 7, 2016

maths
a group of 2 and a group of 3 takes 5 students. Clearly, 10 such pairs of groups can be formed.
November 7, 2016

finance
the net savings rate is 8% Now just plug that into your annuity formula with 35 years of deposits and 30 years of withdrawals. Of course, over 30 years, the 4% inflation will markedly reduce his buying power on a fixed income. A better model would provide for an increasing ...
November 7, 2016

Calculas
v = ?r^2h + 2/3 ?r^3 so, h = (v - 2/3 ?r^3)/?r^2 = v/(?r^2) - 2r/3 the surface area is a = ?r^2 + 2?rh + 2?r^2 = 3?r^2 + 2?r(v/(?r^2) - 2r/3) = 5?r^2/3 + 2v/r da/dt = 10?r/3 - 2v/r^2 = (10?r^3/3 - 2v)/r^2 da/dt=0 when 10?r^3/3 - 2v = 0 r^3 = 3v/(5?) and express h in terms of ...
November 7, 2016

maths - incomplete
Not known, since (a) you did not say how many pictures there are (b) you did not say how many pictures are on a page (that has pictures) Try reading what you write before posting.
November 7, 2016

Math
can't be done 62% = 62/100 = 0.62 Not a whole number
November 7, 2016

Chemistry
Can you check my answers? Thanks!!!! What would happen to the volume-to-temperature ratio if: 1. One student failed to replenish the boiling water in the boiling-water bath as the flask was being heated. At the end of the 6 min of heating, the boiling water in the bath was ...
November 7, 2016

Calculas-Differentiation
you know that f'(2) = 0 2ax+b = 0 at (2,8) 4a+b = 0 4a+2b = 8 So, b=8 a = -2 y = -2x^2 + 8x see http://www.wolframalpha.com/input/?i=-2x%5E2+%2B+8x or, without calculus, you know that -b/2a = 2 since the vertex is there. so b = -4a y(2) = 8, so 4a + (-4a)(2) = 8 a = -2 so ...
November 7, 2016

Algebra
20% less, or 580*.80
November 7, 2016

maths
You keep posting this same stupid problem without enough description to pin it down. AB can be almost any length, depending on the shape of the figure. If the rectangle is ABCD, and the triangle has base CD and vertex E, then still all we know is that AB + 2*AD + 2*DE = 46 Of ...
November 7, 2016

Geometry
do you mean the two sides opposite each of the angles U and V? Normally a side opposite an angle (such as X) is labeled with the lower-case letter of the angle (x) , or the letters of the two vertices at the ends of the side. That would be sides u (VW) and v (UW)
November 7, 2016

business math
well, the amount of interest per day was 278/280 So, the percent interest per day was (278/280)/3800 = .0002613 = 0.02613% Now multiply that by how many days in a year ...
November 7, 2016

arithmetic
hmmm. what is the difference between 7 and 12? How did you get it? Do the same for these two numbers.
November 7, 2016

Maths
just list 'em for MSQ and then replace each letter with the corresponding one from UVW.
November 7, 2016

dynmic
what step by step? The same equation (h = vt - g/2 t^2) applies to both balls, so just set them equal: 30t-4.9t^2 = 50(t-3) - 4.9(t-3)^2 http://www.wolframalpha.com/input/?i=30t-4.9t%5E2+%3D+50(t-3)+-+4.9(t-3)%5E2
November 6, 2016

Math
LB: (360-7)/2 NO: (25-8)/2 Even without doing the actual math, just seeing that much of LB is quite high should make things clear. Now, neither of those averages is -2, but surely NO has a better chance of being near that. What that means is that while the mean of high and low...
November 6, 2016

Math
Sometimes it helps to use the intercept form of a line. 5x - 12y = 60 x/12 + y/-5 = 1 The intercepts are 12 and -5, you you have a 5-12-13 right triangle.
November 6, 2016

Math
It depreciated to 1/2 its value in 6 years. (1/2)^(1/6) = 0.89089 So, the depreciation rate is .1091 = 10.91% per year
November 6, 2016

Calculus
Wll, there is much unsaid here, but if we assume the pyramid has a square base of side length x, and height y, then V = 1/3 x^2 y = 2.2 y = 6.6/x^2 Now, the area of tent is x^2 for the floor 2x?(x^2+4y^2) for the sides So, you want to minimize the cost c = x^2 + 1.4*2x?(x^2+4y...
November 6, 2016

statistics
since the variable of interest is distance, it is continuous. Unless you are measuring the number of shots, which is discrete, but might be involved in a different sampling scheme...
November 6, 2016

math
h/(82*7*60) = sin 13°
November 6, 2016

maths
rectangles and triangles come in many shapes. You need to pin down some of the properties a little more exactly. Is the base of the triangle the same as one of the sides of the rectangle? Anyway, label the sides of your figure, and add them up. They must sum to 46. Can't ...
November 6, 2016

Math
p=3s s=j+4 p+20 = 2(j+20) Now just solve for p.
November 6, 2016

Trigonometry
If we label things as T: town P: plane A: airport Then in triangle TPA, using the law of cosines, 29^2 = 34^2+48^2 - 2*34*48*cosP P = 36.6° Now you can figure out the heading. (the same as the bearing of A from P)
November 6, 2016

science
electron clouds, rather than actual orbits.
November 6, 2016

math algebra
x at 3.5%, so the rest (3000-x) at 2.5% Now just add up the interest: .035x + .025(3000-x) = 190
November 6, 2016

Calc 1
I assume that you mean C(m) = (-.41m^2 + 6.7m - 44)/.7m As you recall from Algebra I, that is C(m) = (1/.7)(-.41m + 6.7 - 44/m) so, C'(m) = (1/.7) (-.41 + 44/m^2) = (1/.7)(44-.41m^2)/m^2 Since the denominator is always positive, C'(m)=0 when 44-.41m^2 = 0 m^2 = 44/.41 ...
November 6, 2016

Calc 1
no. e^(-3x) is never zero, so where is (1-3x)=0? x = 1/3 so, a = (1/3)e^(-3*1/3) = 1/(3e) don't forget your Algebra I now that you're in Calculus!
November 6, 2016

Calc 1
a = xy = xe^(-3x) da/dx = (1-3x)e^(-3x) so, where is da/dx = 0?
November 6, 2016

College Alg
40000(1+.08)^5 Good luck with that!
November 6, 2016

College Alg
P(1+.09/4)^(4*18) = 41000
November 6, 2016

maths
42
November 6, 2016

Algrebra readiness
Not so. Think about your answer. 9+12=21 Those cannot be the sides of a triangle. The 9 and 12 sides would have to lie completely flat on top of the 21 side. The third side must be less than 9+12. In fact, if the 3rd sides is x, 12-9 < x < 12+9
November 6, 2016

PreCalc Oops
oops - that's a+4d=6 But I'm sure you caught that...
November 6, 2016

PreCalc
just crank it out using the formulas you already know: a+5d = 6 12/2 (2a+11d) = 45
November 6, 2016

Calculus
d^2s/dt^2 = -4cos(2t)+sec^3(t)+sec(t)tan^2(t) now just plug and chug.
November 6, 2016

Algebra readiness
?25 + -9 = 5-9 = -14 integer
November 6, 2016

algebra
I thought it was 13/84, but that does not work. However, 1/6 + 1/7 = 13/42
November 6, 2016

Maths
Using discs (washers), they stack up with thickness dy or dx, as needed. (a) v = ?[0,2] ?(R^2-r^2) dy where R=4 and r=x=y^2 = ?[0,2] ?(16-y^4) dy = 128?/5 (b) v = ?[0,4] ?(R^2-r^2) dx where R=2 and r=2-y=2-?x v = ?[0,4] ?(4-(2-?x)^2) dx = 40?/3 Or, you can use nested cylinders...
November 6, 2016

Math, Precalc
can't see your diagram, but consider the vectors representing the diagonals. If it's a unit cube, they might be joining (0,0,0) and (1,1,1) = <1,1,1> (1,1,0) and (0,0,1) = <-1,-1,1> (1,0,0) and (0,1,1) = <-1,1,1> ... Now just take the dot product of ...
November 6, 2016

Calculus
Actually, since f(x)=0 at all those points, we can use Rolle's Theorem, which is just a special case of the MVT were f(a) = f(b) on the interval [a,b]. Both theorems state that f'(c) exists with c in (a,b) such that the tangent is horizontal. That is, f'(c)=0, ...
November 6, 2016

Math-Trigo
Just draw your 5-12-13 triangle in standard position cot(90-A) = tan(A) = y/x = -12/5
November 6, 2016

physic
if 30°, then just find t when the height is zero: 30*sin30° t - 4.9t^2 = 0
November 6, 2016

math
Oops. adding the equations eliminates y. 7x = 28 ...
November 6, 2016

math
You meant: I can't; help me. 5x-2y = 14 2x+2y = 14 ------------- add the two equations 4y = 28 I expect that you can handle it from here, eh?
November 6, 2016

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