Friday
August 22, 2014

Posts by steve


Total # Posts: 24,376

math i need help 3 questions
I'll do #1. How about you show some effort on the others? Just write the words in symbols. If the fraction is n/d, then we are told n/d = 3/4 (n+4)/(d-4) = 4/3 Work through all that, and you have n=12,d=16 check: 12+4 / 16-4 = 16/12 = 4/3 OK
August 15, 2014

math
set it up as a units conversion problem. b books = d dollars, so b bk/d dol = 1 d dol/b bk = 1 That is, books go at the rate of b/d books/dollar, or d/b $/bk Now, you want to convert d books to dollars. You can always multiply by 1, so do it to cancel the units you don't ...
August 15, 2014

math
Nope. (D) Did you draw a diagram? Do so, and label the points. You will have 3 equal sections: AB,BC,CD. AC is twice as long as CD.
August 15, 2014

math
If b lies on ac, then ab+bc = ac x+3 + 2x = 4x-5 x = 8
August 15, 2014

compose
I'm sure that there are those who would consider any of the choices to be the best. It's a purely subject opinion, based on one's own criteria. And what does that (or either of you other posts) have to do with homework?
August 15, 2014

math
nothing to solve. However, if you meant x^2-3x+4 = 0, the two complex values of x that make it true are 3/2 ± √7/2 i If you meant to type x^2-3x-4 = 0, then that factors to (x-4)(x+1) = 0 and it should be clear which values of x are solutions there.
August 15, 2014

trigonometry
If you mean 37°49', then clearly sin 37°49' = 1.5/x now just solve for x, the length of the plank. Oh, and review your basic trig functions.
August 14, 2014

EEeeeeewwww
eeewwww. You've ruined unicorns for me forever!
August 14, 2014

Math - eh?
no idea what all the carets represent.
August 14, 2014

help me
how about you list the six steps. Then apply each step. We'll be happy to check your solution. Wouldn't hurt to bone up on your English, as well...
August 14, 2014

Programming
Try something like this: main() { int x[1000],y[1000],i; for (i=0;i<1000;i++) {read x[i]} y = rev(x,1000); for (i=0;i<1000;i++) {printf("%d ",x[i]} } int *rev(*int,n) { int y[1000],i; for (i=0,n--;i<1000;i++,n--) {y[i] = x[n-i]; return y; }
August 14, 2014

math corrections
Since no coin duplicates the amounts of combining other coins, the number of items could be as many as 4C1 + 4C2 + 4C3 + 4C4 = 15 Note that the sum of the nth row of Pascal's triangle is 2^n, but we are missing 4C0=1, leaving only 15 combinations. This is also the number ...
August 14, 2014

Algebra
from eq #1, 6x = 5y-1 sub that into #2, and you get 5y-1 + 4y = 10 9y = 11 y = 11/9 Now you can get x
August 14, 2014

Algebra
12x+18y+8 <= 80 x+y <= 7 x > 0 y > 0
August 14, 2014

maths
the "rays" instead of "raised" doesn't help any. I read it as ((36/25)^(3/2)) ^ (5/3) due to the sly "whole" meaning "all that has come before". Now, since 36 = 6^2, 36^(3/2) = 6^3 25 = 5^2, 25^(3/2) = 5^3 Now, raise those to the 5/3...
August 14, 2014

math
rectangle: 2(x+2x) = 24 3x = 12 x = 4 So, the rectangle has area 2*4*8 = 64 Now, the square has side 8, so its perimeter is 32.
August 14, 2014

math
the other side, x, satisfies 4.2^2 + x^2 = (x+14)^2 Hmmm. You sure there's no typo?
August 14, 2014

math
a convex polygon with five equal sides. if you google that, you will see many images and descriptions.
August 14, 2014

math
since p = 2(x+y) = 8y, x+y = 4x x = 3y y:x = 1:3
August 14, 2014

Math
see the many related questions below
August 14, 2014

Math
OK. First, it's lookout, not lockout. The man is 25-1.7 = 23.3m up. If the building is at distance x from the tower, and has height h, we have 23.3/x = tan 70°20' (h-23.3)/x = tan 12°40' Now, you can eliminate x, and then solve for h: 23.3/tan70°20'...
August 14, 2014

trigo
As I interpret the data, it appears that the law of cosines will provide our answer. We want the supplement to θ, where 15^2 = 6^2+9^2 - 2(6)(9)cosθ cosθ = -1 Nope, that doesn't work. Maybe you can just describe the figure, giving labels to the points of ...
August 14, 2014

math
If x at 9%, .09x + .10(26000+3x) = 27650 x = 64231
August 14, 2014

Trigonometry
consider the pentagon as 5 isosceles triangles, each with vertex angle of 72°, and sides of 1.5 (the radius). Now you can easily calculate the base of each triangle. The perimeter is 5 times that.
August 13, 2014

Algebra 2
(x-3) / 2x * 6x^2 / 5 (x-3)(6x^2) / (2x)(5) (x-3)(3x)/5 and you can massage that as you will
August 13, 2014

Complex Numbers
if z = x+yi, you have two equations: (x-2)^2 + (y-2)^2 = 23 (x-8)^2 + (y-5)^2 = 38 They intersect at (1/5(20±3√10), 3/5(5∓2√10)) check: (1/5(20+3√10)-2)^2 + (3/5(5-2√10)-2)^2 = 23 You can verify the other.
August 13, 2014

Precalculus
If z = a+bi, we have (1+i)(a+bi) - 2(a-bi) = -11+25i Expand all that out and you get (-a-b)+(a+3b)i = -11+25i So, that means that -a-b = -11 a+3b = 25 a=4 b=7 So, z = 4+7i
August 13, 2014

Precalculus
I'd just multiply: (4-5i)^2 + (a+8i)(4-5i) + (-39+bi) = 0+0i Expand all that out and you have two equations in a and b. I get a = 2 b = 18 So, that leaves us with z^2 + (2 + 8i) z + (-39 + 18i) = 0 and the other root is thus -6 -3i
August 13, 2014

math test review
You know that 5^2 = 25 6^2 = 36 34 is less than 36. Now what do you think?
August 13, 2014

Math
no such number exists. Such terminology is bogus. If you mean 41 ten-thousandths, that would be 0.0041 You can have 41 thousand, but not 41 ten thousand.
August 13, 2014

Math
150% none (should be 70%) recall that 1.0 = 100%
August 13, 2014

Calculus (need help with only d and e)
The 2nd pill is shifted by 60 minutes. So, if the 1st pill is modeled by f(x), the 2nd pill will be modeled by f(x-t). Now just work with the new f(x).
August 13, 2014

maths
If you mean 9^(2x+1) = 81^x / 3^x expressing all as powers of 3, we have 3^(4x+2) = 3^3x so, 4x+2 = 3x x = -2 check: 9^-3 = 81^-2 / 3^-2 = 9^-4/9^-1 = 9^-3
August 13, 2014

algebra
your writing is so full of typos it's incomprehensible. When you get an answer, test it to see whether it works in the original equation.
August 13, 2014

Algebra
you could easily have verified it on your handy dandy calculator. Can't believe you went to the trouble of posting such an easy thing to check.
August 13, 2014

math
(25+12*15)*.12
August 13, 2014

Algebra
Your work so far is correct.
August 13, 2014

statistic
.20 * .30
August 13, 2014

statistics
Oops. I misread (b). My answer is ~rain & windy
August 13, 2014

statistics
(a) .20 * .30 = .06 (b) (1-.20) * .30 = .24 (c) .20 + .30 - .20*.30 = .44 (d) (1-.20) + (1-.30) - (1-.20)(1-.30) = .94 Note that (d) = 1-(a)
August 13, 2014

math
2pi = 6.28 so, you have 2pi r = C 6.28r = 27 now just divide by the 6.28 as usual to get r.
August 13, 2014

Math
You know that for the parabola y^2 = 4px It opens to the right The LR is 4p (So, if the shifted parabola is (y-k)^2 = 4p(x-h), our points and LR say (1-k)^2 = (3-h) (5-k)^2 = (-5-h) so, the parabola is (y-4)^2 = (x+6) So, now you have a 3rd point: the vertex at (-6,4) Now it&#...
August 13, 2014

Algebra
#1. x(2400-2x) #2. x(1800-6x)/2 Both of these are just parabolas, where the maximum area occurs at the vertex of the parabola. Recall that for y = ax^2+bx+c, the vertex is at x = -b/2a
August 13, 2014

maths
clearly, d = 3/2. So, if the first term is a, a(a+3d) = 34 a(a+9/2) = 34 . . .
August 13, 2014

math
Surely your text has sections on these topics. I expect that the accompanying graphs and sample problems there will be at least as good as any impromptu explanations here. Do a google on any of the above topics for many discussions. After that, if there's some kind of ...
August 13, 2014

math
http://www.wolframalpha.com/input/?i=x%2B2y-z%3D6
August 13, 2014

maths
total distance: 240 miles total time: 120/60 + 120/40 = 2+3 = 5 hours avg speed: 240/5 = 48 mph
August 13, 2014

geometry
why bother with a? Just prove x=7. 3(2x+4)+18 = 72 6x+12+18 = 72 6x = 42 x = 7
August 13, 2014

maths
3@5 = 3(5-3) = 6, so 4@(3@5) = 4@6 = 4(6-4) = 8
August 13, 2014

algebra
almost. If 2n=78, n=29 If 1/2 n = 78, n = 156 We customarily use a caret, as in 3^4, to indicate powers.
August 13, 2014

math - typo
10% of 4 is 0.4 None of the choices works. I suspect a typo in your presentation.
August 13, 2014

Math
If there were x 2-pointers and y free throws, then we know x+y = 18 (add the shots) 2x+y = 35 (add the points) Now just solve for x and y.
August 12, 2014

math
just as 5-3 = 2, 5/6 - 3/6 = 2/6 However, the instructions say to write the simplest form, so 1/3 would be my choice.
August 12, 2014

Math
Does 7 divide 3? Nope, so that cannot be a factor of 3u^3... List all the factors of each term: 3 u^3 x^5 y^8 3 7 u^6 x^5 Now pick the highest power of each prime or variable that appears in both terms: 3 u^3 x^5 That is the GCF.
August 12, 2014

math
you already have one pair: (1,1.50) Now just pick any positive integer, and multiply it by 1.50. That will give you other pairs: (2,3.00) (102,153.00) (9231,13846.50) For convenience of graphing, I'd stick with small numbers, though! :-)
August 12, 2014

math trigonometry
Draw a diagram, as usual. If the post is x meters from the house, which has height h, h/x = tan 45° = 1 So, h = x (h-20)/x = tan 30° = 1/√3 But, h=x, so (h-20)/h = 1/√3 h-20 = h/√3 (1-1/√3)h = 20 h = 20/(1-1/√3) = 47.32 m
August 12, 2014

Math
Oops. g◦f and f◦g are not onto, since (g◦f)(0) = 0 (g◦f)(1) = 2 And there is no x such that (g◦f)(x) = 1 (f◦g)(0) = 1 (f◦g)(1) = 1 (f◦g)(2) = 4 and there is no (f◦g)(x) = 2
August 12, 2014

Math
clearly g is not 1-1. For example, g(3) = g(2) Also, it is clear that both f and g are onto. Some good discussion can be found here: http://www.csee.umbc.edu/~stephens/203/PDF/7-3.pdf f◦g = 3g+1 = 3⌊x/2⌋+1 g◦f = ⌊f/2⌋ = ⌊(3x+1)/2⌋...
August 12, 2014

arithematic
the middle value is (51+64)/2 = 57.5 That is 6.5 away from each end, so |x-57.5| <= 6.5 See the graph at http://www.wolframalpha.com/input/?i=|x-57.5|+%3C%3D+6.5
August 12, 2014

arithematic
If the dimensions of the garden are x and y, with the building along side x, then x+2y = 81 So, the area (xy) is (81-2y)y = 81y - 2y^2 This is a parabola, with vertex at y=20.25 Now you can figure the other dimension. I suspect you meant to say 80 ft of fencing, but only you ...
August 12, 2014

Math
If the strip has width w, the pool is 60-2w by 80-2w So, (60-2w)(80-2w) = 1/6 (60)(80) Now just solve for w.
August 12, 2014

Math
If the dimensions of the whole garden are x and 2y (because there are two adjacent gardens, each x by y), 2x+4y = 100 2xy = 400 or, x+2y = 50 xy = 200 since x = 50-2y, (50-2y)y = 200 50y - 2y^2 = 200 y^2-25y+100 = 0 y = 5 or 20 So, x = 40 or 10 The garden is 10 by 40.
August 12, 2014

6th grade math
count the coins: n = d+13 count the value: 5n+10d = 440 5(d+13)+10d = 440 5d+65+10d = 440 15d = 375 d = 25 So, there are 25 dimes and 38 nickels
August 12, 2014

Algebra
A pair of jeans is on sale for 25% off the original price. Write an expression that represents the sale price? If the original price of the jeans is $40, evaluate the expression to find the sale price. My answer is s = p-0.25 p; $30
August 12, 2014

Analytic Geometry
(a) x^2+y^2 = 4 (b) surely you know how to figure the area and circumference of a circle of radius 2. (c) subtract that area from the area of the triangle. This is because the entire circle is within the triangle.
August 11, 2014

Analytic Geometry
Solving the equations in pairs, you find the vertices to be (2,5),(5,-1),(-3,-5) Now you can figure the incenter and inradius of the triangle. The equation of the circle is then easy.
August 11, 2014

Algebra - eh?
It appears you have something to do with the Pythagorean Theorem, but it's not immediately clear just what.
August 11, 2014

coor. algebra
work with units, just as with numbers. When doing conversions, just recall that you can always multiply by 1 and nothing is changed. You want to convert meters into miles, and seconds into hours. 3600 seconds = 1 hour So, 3600sec/hr = 1 Similarly, 1km = 1000m = 0.62 miles, so...
August 11, 2014

Analytic Geometry
Or, you can take the slopes of the sides. AB has slope 1/3 AC has slope 3/2 So, measuring as usual, angle A is arctan(3/2)-arctan(1/3) = 236.31°-198.43° = 37.88°
August 11, 2014

Algebra
all correct. Though I'd have written #2 as (9+5z)(9-5z) to associate it more readily with the difference of two squares.
August 11, 2014

math
.19a + .22b = 36.12 175a + 80b = 30080 a = 160 b = 26
August 11, 2014

math
5*5*5 = 125 she has 5 choices for each part.
August 11, 2014

Algebra
30w^4v^8 = 2*3*5 w^4 v^8 24y^3w^6v^2 = 2^3*3 y^3 w^6 v^2 The GCF is the highest powers of the factors that appear in both terms: 2*3 w^4 v^2 = 6w^4v^2 No other combination of factors and higher powers divides both terms
August 11, 2014

math corrections
if x=8, 8x = 64 so, now you have (4y)^2 = 64 Since 64=8^2, 4y can be 8 or -8
August 11, 2014

math corrections
If P(win) = p, P(lose) = 1-p p = 2/7 (1-p) so, p=2/9, 1-p = 7/9
August 11, 2014

Algebra
What is an algebraic expression for 5 more than z? My answer is z5
August 11, 2014

polynomials and polynomial functions
If you factor it, things should become clear: 3z(z^2-100) = 0 3z(z-10)(z+10) = 0
August 11, 2014

math
If you meant (1+sec20° cot20°)(1-csc20° tan20°) Then you have sec20° cot20° = csc20° csc20° tan20° = sec20° and the product becomes (1+csc20°)(1-sec20°) I don't see anything much else to do.
August 11, 2014

Algebra
Is 3 A an example of an algebraic expression? My answer is yes
August 11, 2014

Algebra
What is the word phrase for the Algebraic expression 4 (21 n)? My answer is 4 times the product of 21 and a number N
August 11, 2014

Algebra
well, 8 less than N is N-8, the product of 12 and x is 12x, so 12x-8
August 11, 2014

Algebra
What is the algebraic expression for the word phrase 8 less than the product of 12 and a number x.
August 11, 2014

Maths
check the definition of cosine. cos 65° = 15.5/length
August 11, 2014

mathematics
huh. what is 3 more than 2? Now just write down the digits in the right order.
August 11, 2014

maths
what is the smallest number divisible by both 6 and 8? 6 = 3*2 8 = 4*2 Every factor has to appear, so, you need 3*4*2 = 24
August 11, 2014

math
just plug in your numbers, using the amortization formula.
August 11, 2014

Math
D = |3 2| |2 3| = 5 Dx = |-3 2| |8 3| = -25 Dy = |3 -3| |2 8| = 30 x = Dx/D = -26/5 = -5 y = Dy/D = 30/5 = 6
August 11, 2014

math
plug in your data at http://www.gregthatcher.com/Mathematics/GaussJordan.aspx and see all the details unless you meant to use matrix inverses.
August 11, 2014

Math
(-4)(8) - (6)(-6) = -32 + 36 = 2
August 11, 2014

Algebra
your typos make it unclear whether you want y = 35x or y = x/35
August 10, 2014

Accelerated Algebra
so far, so good. The area of such a rectangle is x(40-x) = 40x - x^2 You want 40x - x^2 >= 350 -x^2 + 40x - 350 >= 0 Now, the roots of this function are 12.9 and 27.1 Since it is a parabola opening down, y is positive for x between the roots. So, for any value of x ...
August 10, 2014

math
I chose wolframalpha.com, which you can always use to verify your solutions. http://www.wolframalpha.com/input/?i=solve+10x%2By%3D278%2C+10y%2Bx%3D107+
August 10, 2014

math
v-w = -3 -x+y = 3 adding them up gives 0
August 10, 2014

java
in perl, $sum = 1; $sum += $n/$x**$n foreach $n (2..$r); print $sum; I leave it to you to provide values for x and r.
August 10, 2014

Math
g/b = 2/7 b = g+250 now just solve.
August 10, 2014

maths
looks ok to me.
August 10, 2014

math
if the triangle has side s, it has area = √3/4 s^2 perimeter = 3s if the circle has radius r, it has area = πr^2 perimeter = 2πr so, 3s+2πr = 12 s = 4 - 2π/3 r and we want to minimize the area a = √3/4 s^2 + πr^2 = √3/4 (4 - 2π/3...
August 10, 2014

calculus
df/dt = 1.2 - 0.24t now just plug in t=8
August 10, 2014

calculus
PI, not pie! It's a Greek letter, not a dessert. iv v = 2πr^2, dv/dr = 4πr now just plug in r=4 However, for a cone of height 8, v = 8/3 πr^2 If that's what you want, make the necessary change to the above logic.
August 10, 2014

math
List the factors of 81: 1,3,9,27,81 Pair them up and you have the available dimensions.
August 10, 2014

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