Saturday
June 25, 2016

Posts by Reiny

Total # Posts: 35,067

Quadratic Functions2
This question and the other one I just answered for you are fundamental questions that you just have to know how to do in this topic. To simply say, "I can't figure out how to get the answer" tells me you are not even in the course. Anyway.... since you know the ...
June 1, 2016

Quadratic Functions1
1. f(x)= 3(x-2)^2-6 with zeros of 0.59 and 3.41 everything you asked for , except the y-intercept, can simply be stated directly from the equation: x-intercepts, you stated them already axis of symmetry: x-2 = 0 or x = 2 vertex: (2,-6) for the y-intercept, let x = 0 y = 3(-2)^...
June 1, 2016

@ Kaitland and Othilia - Algebra
The purpose of this webpage is not to facilitate cheating. You are in danger of being banned from using it.
June 1, 2016

mathhhhhh plz help immediately
is that X^3=36.31*10^-24 ? if so , just take the cube roots of that number. I get (36.31)^(1/3) * 10^-8 or appr 3.3114 * 10^-8
June 1, 2016

Math- Prob Stat
The absolutely perfect webpage for your question. Just plug in the values http://davidmlane.com/normal.html
June 1, 2016

math plz help ;-;
Is the top of the ice-cream a hemisphere? "On top of the cone is 18 as the bottom is 26. " This makes no sense to me. I need the radius of the cone, and the height of the cone. (The radius of the hemisphere is determined by the radius of the cone)
June 1, 2016

math plz help ;-;
Consider the following properties of a triangle 1. If a triangle has an obtuse angle, that angle must be opposite the largest side 2. A triangle can have at most one obtuse angle 3. If a triangle has sides a, b, and c, with c as the largest side, then if -- c^2 > a^2 + b^2...
June 1, 2016

stats
number of possible 5-digit pins = 3x3x3x3x3 = 243 prob(same) = 1/243
June 1, 2016

math plz help ;-;
slope is (-7-8)/(1+4) = -15/5 = -3 so y = -3x + b plug in one of your points, I picked (-4,8) : 8 = -3(-4) + b ---> b = -4 so y = -3x - 4 now, how easy was that?
June 1, 2016

Math - system of eqns
1 1 1 | 6 -1 -2 3 | 1 3 -4 4 | 5 1 1 1 | 6 0 -1 4 | 7 from: add #1 and #2 0 7 -1 | 13 from #3 x 1 - #3 1 1 1 | 6 0 -1 4 | 7 0 0 27| 62 from #2 x 7 + #3 1 1 1 6 0 1 -4 -7 switch signs 0 0 1 62/27 divide by 27 so x3 = 62/27 now back substitute x2 - 4(62/27) = -7 x2 = 248/27 -7...
June 1, 2016

math
let the times for the 3 subjects be 2x, 3x and x hrs each 2x+3x+x = 8 6x=8 x = 4/3 science : 2(4/3) = 8/3 hrs or 2 hrs and 40 minutes Math : 3(4/3) = 4 hours Lit : 4/3 hrs or 1 hour and 20 minutes check: 2:40 + 4:00 + 1:20 = 6:00
June 1, 2016

Radicals
not sure of your notation. does ^3 root -192 supposed to mean the cuberoot of -192 ? if so , (-192)^(1/3) = (-64)^(1/3) * (3^(1/3) = -4 (3)^(1/3) or -4 cuberoot (3) -6 exponent 3root 13 ?? = (-6)^3 √13 ???
May 31, 2016

Adding and subtracting mixed numbers
I would do it this way: (4 1/8 + 6 1/4) - 2 1/2 first of all, there is no need for the brackets in this case secondly, I change all my mixed fractions to workable fractions = 33/8 + 25/4 - 5/2 LCD is 8 = 33/8 + 50/8 - 20/8 = 63/8 or 7 7/8 mixed numbers are "nice" to ...
May 31, 2016

Algebra
First of all: you don't have an equation to solve are you simplifying? Your run-ons of "over" have to bracketed to establish priority e.g. is it ( (1+1/x)/x ) / (1/(x-1) ) or ( (1+1/x)/x ) / (1/x-1) ) or ...
May 31, 2016

math plz help ;-;
easiest way: for the y-intercept, let x = 0 , (can be done mentally) so -3y=12 ----- > y = -4 You are probably using the equation in the form y = mx +b, where b is the y-intercept, so change your given equation to that form 2x - 3y = 12 -3y = -2x + 12 divide by -3 y = (2/3)...
May 31, 2016

Maths (quadratic equation) need help
base ---- x height ---2x-3 area of triangle = (1/2) base x heigh (1/2)(x)(2x-3) = 10 carry on
May 31, 2016

Maths (quadratic equation) need help
using their hint: let the numerator of original fraction be x then the denominator is 2x+1 so the original fraction is x/(2x+1) condition stated: x/(2x+1) + 2 1/10 = (2x+1)/x x(2x+1) + 21/10 = (2x+1)/x multiply each term by 10x(2x+1) , the LCD 10x^2 + 21x(2x+1) = 10(2x+1)^2 ...
May 31, 2016

Math - Vectors
a) u = (-1, 2, -1) , v = (2, -1, 0) , w = (1, 1, -1) b) you want the cross-product of u and v, that is, a vector which is perpendicular to both u and v I don't know which method you have learned, but you should get (1, 2, 3) c) the normal to the triangle is (1,2,3) so the ...
May 31, 2016

Math - Year 10 - Probability
I can't solve the question, because there was no question.
May 31, 2016

math help
1,127.5 milligrams = 1.1275 grams ahhh, the beauty of the metric system !
May 31, 2016

maths
When I answered this question there was another solution after Steve's which has now been deleted. I only completed Steve's solution to correct that other posting.
May 31, 2016

maths
from Steve's ... 1/x + 1/y = 7/20 times 20xy, the LCD 20y + 20x = 7xy 20(y+x) = 7xy 20(14) = 7xy 40 = xy -----> y = 40/x plug into the first: x + 40/x = 14 x^2 + 40 - 14x = 0 (x-10)(x-4) = 0 x = 10 or x = 4 if x = 10, y = 40/10 = 4 if x = 4 , y = 40/4 = 10 the numbers ...
May 31, 2016

Math Calculus I
your f ' (x) is correct but not complete f ' (x) = (9*(cos^2(x)+sin^2(x)))/(3cos(x)+sin(x))^2 remember that sin^2 x + cos^2 x = 1 f '(x) = 9/(3cosx + sinx)^2 so when x = π/6 , f'(π/6) = 9/(3√3/2 + 1/2)^2 = appr .93769 this is the slope of the ...
May 30, 2016

math
Assuming you made your sketch, angle SOT + angle E = 180° , (since the angles at S and T are each 90° ) angle SOT + 78 = 180 angle SOT = 102° so the arc SOT = 102/360 of the circumference = 17/60 of the circumference
May 30, 2016

Math - volume about y axis
Makes no sense to me neither. f(x) = x^2 - 1 is a parabola opening upwards, so when we revolve it about the y-axis we have it open-ended above. We need a closed region to revolve. Did you mean the region below the x-axis ?
May 30, 2016

Algebra 1
length = 4x-3 Width = x-4 2W + 2L = perimeter 2(4x-3) + 2(x-4) = 84 8x - 6 + 2x - 8 = 84 10x = 98 x = 9.8
May 30, 2016

Trigonometry
sketch a right-angled triangle . since cosØ = 2/5 = x/r x^2 + y^2 = r^2 4 + y^2 = 25 y^2 = 21 x = ±√21 case 1: if x = +√21 cosØ = 2/5 , sinØ = √21/5 cos 2Ø = cos^2 Ø- sin^2 Ø = 4/25 - 21/25 = -17/25 case 2: if ...
May 30, 2016

Math..help
you should memorize the pattern for squaring a binomial: (a - b)^2 = a^2 - 2ab + b^2 so (3a - 7/9)^2 = 9a^2 - 42/9 a + 49/81 = 9a^2 - (14/3) a + 49/81
May 30, 2016

Math (Polar to Cartesian Equations)
secØ = r/x , cscØ = r/y so r^2 = 4(r/x)(r/y) r^2 = 4r^2/(xy) 1 = 4/(xy) xy = 4
May 30, 2016

math
just sub into the basic formula: amount = 400(1.07)^t
May 30, 2016

Math help!
#5 7^4/7^2____ 49 7^2 ______ 49 49 _____ 49 care to re-evaluate your answer? #6 –2r(8r + 5) = -16r^2 - 10r #7 correct #8. (2y – 3) (3y – 2) = 6y^2 - 4y - 9y + 6 = 6y^2 - 13y + 6 mmmmhhh, 1 out of 4 correct, somebody needs more studying and review.
May 30, 2016

math
arc cd=90° ?? this makes no sense, since arc length is measured in linear units , not degrees Are you saying that the arc cd subtends a 90° angle at the centre? If so, then r^2 + r^2 = 12^2 2r^2 = 144 r^2 = 72 r = 6√2 area of whole circle = 72π inches^2 area...
May 30, 2016

Math
correct
May 30, 2016

math
width --- x length --- x+4 solve for x x(x+4) = 117 hint: the quadratic factors nicely.
May 30, 2016

Math
Poorly worded question. Assuming her position is at the origin, and assuming by "path of ball" you mean the height of the ball, and assuming the net is at (20,10), and assuming the ball lands 5 ft beyond the net, we could have .... height = ax(x-25) subbing in (20,10...
May 30, 2016

algebra
300 ft/2.92 seconds = (300/5280) miles / (2.92/3600) hrs = (300/5280)(3600/2.92) mph = 70.05 mph = appr 70 mph
May 30, 2016

math
calculate the distance for different values of t e.g. t = 0, D(0) = -1.5(-8) + 9 = 21 t = 1, D(1) = 19.5 ... t = 5 , D)5) = 13.5 .. t = 8 , D(8) = 9 .. t = 12 , D(12) = 3 t = 15 , D(15) = -1.5 This question does not make any sense to me
May 30, 2016

maths
I don't understand your question. Please proofread and repost. Where does C suddenly come from ?
May 30, 2016

Math
L --- linear N --- non-linear xy = -9 --- N y = 3x --- L x + 7 = y --- L y = x - 4 --- L y = x^2 --- N x + y - 20 = 2x --- L 1/2x = y ---- L y = 5/x ---- N y = 30 - x^2 ---- N Did you notice why some are L and some are N ?
May 30, 2016

Math
Make a sketch to see that r = 5, h = 3 then s^2 = 5^2 + 3^2 = 34 slant height = √34 cm circumference of base of cone = 2π(5) = 10π cm This becomes the arc-length in a circle of circumference of 2π√34 let the angle of the sector be Ø arc = r&...
May 30, 2016

math plz help ;-;
Since both equations contain 2x, the easiest way would be elimination, thus subtract them: -4y = -2 y = -2/-4 = 1/2 sub into the first: 2x - 5(1/2) = -1 2x = 5/2-1 = 3/2 x = 3/4 ---------> x = 3/4 , y = 1/2 #2 y=(3/5_x-1 y=6/10x+3 ----> y = (3/5)x + 3 since you have two ...
May 30, 2016

math
(1.4*10^1)(8*10^4) = 11.2 * 10^5 = 1.12 * 10^6
May 29, 2016

Geometry
tan 43° = height/250 solve for "height"
May 29, 2016

CORRECTION - Maths , logarithms
#1 answer is incorrect 2^x * 6^x = log 14 14^x = log 14 now take logs of both sides, and use log rules x log14 = log(log14) x = log(log14)/log14 = appr .05168 it is easy to show that x = 1 is not a solution to the question since 14^1 ≠ log14 #2 2^2x+1 - (9)2^x = -4 the ...
May 29, 2016

Algebra
number of generals (student?) --- x , x ≥ 300 number of adults ----- y , y ≥ 500 ad cost = .5x + 1y , where .5x+y ≤ 400 profit = 6x + 9y - .5x - y = 5.5x + 8y The question cannot be answered e.g. If we allow the min of each x = 300, y = 500 profit = 5.5(300...
May 29, 2016

algebra
Just translate into math: shortest side --- x longest side ---- x+7 remaining side --- x+2 solve: x + x+7 + x+2 = 45
May 29, 2016

Math
(2/5)x + 15 = 27 solve for x
May 29, 2016

Math
let the 3 consecutive odds be n, n+2, and n+4 n+n+2+n+4=69 3n = 63 n = 21 They are 21, 23, and 25, with 23 as the prime one
May 29, 2016

Maths
I see a recursive formula: term(n) = term(n-1) + (n-1)^2 , for n > 1 , term(1) = 0 term(1) = 0 term(2) = 0 + 1^2 = 1 term(3) = 1 + 2^2 = 5 term(4) = 5 + 3^2 = 14 term(5) = 14 + 4^2 = 30 term(6) = 30 + 5^2 = 55
May 29, 2016

Math
average score of first three test is 90 ----> sum of those 3 tests was 270 average score of two test is 89 ---> sum of those 2 tests = 178 avg of 5 tests = (270 + 178)/5 = 89.6
May 28, 2016

Math
The volumes of two similar objects are proportional to the cube of their sides so vol1 : vol2 = 2.6^3 : 3.4^3 = 13^3 : 17^3 = 2197 : 4913 note: 2.6/3.4 = 26/34 = 13/17
May 28, 2016

algebra
If you meant: 7a^4 b , then the degree would be 5
May 28, 2016

Algebra
base ----- x cm height ---- 2x-4 cm area of triangle = (1/2) base x height (1/2)(x)(2x-4) = 48 x(2x-4) = 96 2x^2 - 8x - 96 = 0 x^2 - 4x - 48 = 0 (x-8)(x+6) = 0 x = 8 or x = -6, the latter is inadmissable base is 8 cm height is 12 cm
May 28, 2016

Maths
length of trail ---- x miles x/15 - x/20 = 8/60 times 60 , the LCD 4x - 3x = 8 x = 8 the trail is 8 miles long check: time at 20 mph = 8/20 hrs = 24 minutes time at 15 mph = 8/15 hrs = 32 minutes for a difference of 8 minutes
May 28, 2016

Calc
Because of summetry, we only need to look at the first quadrant Area of whole thing in quadrant I = ∫(16 - 4x^2) dx from 0 to 2 = [16x - (4/3)x^3] from 0 to 2 = 32 - (4/3)(8) - 0 = 64/3 So the area created by y = b must be 32/3 the intersection of y = b and y = 4x^2: 4x^...
May 27, 2016

Go with Steve - Calculus
My answer is gibberish I read it as area not volume, the irony is that I used to stress "Read the question carefully at least three times"
May 27, 2016

Calculus
Then you simply have area = ∫ (5 - 1/x) dx from 1 to 4 = [5x - lnx] from 1 to 4 take over after you found your answer , look at http://www.wolframalpha.com/input/?i=area+between+y+%3D+5+and+y+%3D+1%2Fx+from+1+to+4
May 27, 2016

Calculus
area = ∫ 1/x dx from 1 to 4 = [lnx] from 1 to 4 = ln4 - ln1 = ln4 - 0 = appr 1.3863 confirmation: http://www.wolframalpha.com/input/?i=%E2%88%AB+1%2Fx+dx+from+1+to+4 b) not sure about the y = 5 Are we rotating about y = 5 instead of the x-axis? Do we still have x = 1 to ...
May 27, 2016

math
do we know how many bottles in a case?
May 27, 2016

MATH - CALC
f(x) = x^3 - 3x^2 = x^2(x-3) You should be familiar with the general shape of y = 1x^3 + ..... yours crosses at x = 3 and since you have a double root at x = 0, it touches the x-axis at x = 0 find f'(x) and f''(x) , that should be easy when f'(x) is positive, ...
May 27, 2016

math
really? You are studying the above topic and you are asking this question? Sorry, but .....
May 26, 2016

math
"first term in an arithmetic sequence is 15" ---> a=15 "the tenth term is 69" ---> a+9d = 69 sub in a = 15 to find d then evaluate a + 3d
May 26, 2016

math
I will assume d is the diameter. so r = 4, h = 12 V = (1/3)π r^2 h plug in your values
May 26, 2016

Math
what is 1.35(29.50) ?
May 26, 2016

math
speed of plane without wind ---- x km/h speed of wind --------- y km/n 5600/(x-y) = 8 700/(x-y) = 1 x-y = 700 ** 9900/(x+y) = 9 1100/(x-y) = 1 x + y = 1100 *** add ** and *** to find x then sub back into **
May 26, 2016

math
Very very unsafe placement of a ladder.
May 26, 2016

Ratios math
cars : SUV's = 4:1 = 16:4 SUV's : Minivans = 4:5 now that I have a common "4" for the SUV's in both, I can say cars : SUV's : minivans = 16 : 4 : 5 or = 16x : 4x : 5x but 5x = 20 x = 4 so we have 64 cars, 16 SUV's , and 20 minivans for a total of ...
May 26, 2016

Math
Kiki, I found the 2.5 seconds for you in your previous post. Just sub that value into your equation. then do it again for t = 4 let me know what you got.
May 26, 2016

Math
what is C(5,2) x C(3,1) ?
May 26, 2016

Math
equivalent to finding the vertex of the parabola h = -16t^2 + 80t + 6 the t of the vertex is -b/(2a) = -80/-32 = 2.5 seconds
May 26, 2016

math
@ sad/jeo 6 almost identical questions without any work shown or indication where your problems are. Steve and I have answered 3 of them. Surely you can do the rest by following our methods.
May 26, 2016

math
if selling at 600 is a loss of 25%, the cost was .75x = 600 x = 800 so make a profit of 25% on the 800 , he should have sold at 800(1.25) = 1000
May 26, 2016

math
cost of first = 240/1.2 = 200 cost of 2nd = 240/.8 = 300 percentage change = (200+300)/480 = 1.04166.. he made a profit of appr 4.17%
May 26, 2016

precal
two numbers: x and y xy = 48 ---> y = 48/x and 1/x + 1/y = 1/3 (x+y)/(xy) = 1/3 (x+y)/48 = 1/3 x+y = 16 x + 48/x = 16 x^2 + 48 = 16x x^2 - 16x + 48 = 0 (x-12)(x-4) = 0 x = 12 or x = 4 if x = 12, y = 48/12 = 4 if x = 4, y = 48/4 = 12 The two numbers are 12 and 4
May 25, 2016

Pre-cal
cos^2 x = 3/4 cosx = ± √3/2 x = 30°, 150°, 210° or 330° in radians: π/6, 5π/6, 7π/6, 11π/6
May 25, 2016

Math
Your question is not clear at all. Are we first selecting the committees, then picking the president and vp ? number of committees = C(11,5) = 462 to pick a president , then vice president, order does matter, so 11x10 = 110 or P(11,2) if we are picking the pres and vpres from ...
May 25, 2016

algerba
the usual way to type a power is to use the ^ to show exponents, e.g. x^2 is "x squared" 0 = −2x^2 − 3x + 8 in standard form is 2x^2 + 3x - 8 = 0 so b^2 - 4ac = 9 - 4(2)(-8) = ...... 4(x + 2)^2 = 36 divide both sides by 4 (x+2)^2 = 9 x+2 = ±√...
May 25, 2016

Math/ ratios/ Fractions/ Singapore Math
Ross' total --- x Holly's amount = 60-x after spending: Holly has (3/4)(60-x) Ross has x-5 given: Holly/Ross = 1/2 (3/4)(60-x) / (x-5) = 1/2 45 - (3/4)x / (x-5) = 1/2 90 - (3/2)x = x - 5 180 - 3x = 2x - 10 190 = 5x x = 38 take over, using my definitions at the top
May 25, 2016

Math/ more ratios
let the number of pennies they have be 6x , 5x and 7x respectively 6x + 5x + 7x = 754 18x = 754 x = 41.88.. you are right, it makes no sense, it has to be a whole number. I suspect a typo in the question in your text or whatever your source.
May 25, 2016

correction - College Algebra
You cannot take log of individual terms, you have to take log of both sides. i.e. log (3^n + 9) = 69 but , why not just do this: 3^n = 60 now log both sides, and use log rules: n log3 = log60 n = log60/log2 = appr 3.727 check: 3^3.727 + 9 = 69.01100 , close enough to 69 if you...
May 25, 2016

math
amount of her money --- x after spending 2/7 of it, she has (5/7)x left then she spends (2/5) of that, or (2/5)(5/7)x total amount spent = (2/7)x + (10/35)x = (2/7)x + (2/7)x = (4/7)x so (3/7)x = 15 3x = 105 x = 35 <------ money she started with check: she spends (2/7)(35) ...
May 25, 2016

school
Things you learn from Google: http://www.shmoop.com/walk-two-moons/margaret-cadaver.html Ironic: At the top of the webpage it showed an ad for Plagiarism software
May 25, 2016

math
his cost price = rs 16 so his selling price should be 1.15(16) or rs 18.4 per dozen. But you want the selling price per hundred so : 18.4/12 = x/100 x = 100(18.4)/12 = 153.333... (notice the fact that he bought 1200 eggs did not enter the calculation) check: cost price per ...
May 25, 2016

Calc-Math
your derivative is wrong, the xy needs a product rule 2y dy/dt + x dy/dt + y dx/dt - 3dx/dt = 0 plugging in our stuff 2 (-4) + 3(-4) + 1(dx/dt) - 3 dx/dt = 0 -2 dx/dt = 20 dx/dt = -10
May 24, 2016

Calculus
so your equations can be written as y = 1/√x and y = 1/x^2 let's look at their graphs: http://www.wolframalpha.com/input/?i=plot+y+%3D+1%2F%E2%88%9Ax+,+y+%3D+1%2Fx%5E2 ignore the part for x<0 , since in y = 1/√x, x > 0 so let's take horizontal slices ...
May 24, 2016

Financial Math
clearly repetition would be allowed in passwords, and I would assume we can start with zero as well number of passwords = (10^3)(26^2) = ...
May 24, 2016

Algebra
youngest ---- x oldest ---- 2x (2x + 12 + 15 + x)/4 = 13.5 3x + 27 = 54 take over
May 24, 2016

Math
let the point on the line be (x,y) line is y = (4-x)/4 = 1 - (1/4)x area of rectangle: A = xy = x( 1 - (1/4)x) = x - (1/4)x^2 this is a downwards parabola. We need the vertex the x of the vertex is -b/2a = -1/(-1/2) = 2 then y = 1- (1/4)(2) = 1/2 max area = xy = 2(1/2) = 1 ...
May 24, 2016

Math
a coefficient is simply the number in front of the variable. So it is -7
May 24, 2016

Algrebra Help!
just plug in n = 1 n = 2 n = 3 n = 4 and evaluate. e.g. n = 3 value is 3(3-2) - 3 = 3(1) - 3 = 0
May 24, 2016

Math
let the unit digit be x let the tens digit be y the number is 10y + x 10y + x = 2(y-x) 10y + x = 2y - 2x 8y = -3x mmmmhhhh? do you have a typo?
May 24, 2016

German
#1 Beantwortest du die Fragen ? - Are you answering the questions ? Fragtest du die Fragen? - Had you asked the questions ? Either one would actually be acceptable, depending which idea you were trying to convey. #2 by the process of elimination, I have to say Wir lernen ü...
May 24, 2016

Algebra
yup!
May 24, 2016

pre-algebra
agree
May 24, 2016

geometry
mmmhhh, did you plot your points? Can you see any way they could form a rectangle?
May 24, 2016

math
You did not specify whether you want degrees or radians. I will do it for degrees. Repeat for radians, make sure to set your calculator to radians 3sec^2 y = 5(1+tany) We know sec^2 A = 1 + tan^2 A 3(1 + tan^2 y) = 5(1 + tany) 3 + 3tan^2 y = 5 + 5tany 3tan^2 y - 5tany - 2 = 0...
May 24, 2016

math
#1 cos(x+20) = sin(90 - (x+20) ) , one of the basic rules but sinx = cos(x+20) sinx = sin(70-x) arcsin both sides x = 70-x 2x=70 x = 35 check: LS = sin 35 RS = cos(35+20) = cos 55 but cos 55 = sin 35 so all is good tanx = sinx/cosx = cos(x+20)/cosx = (cosxcos20 - sinxsin20)/...
May 24, 2016

Math
SA = 2lw + 2 lh + 2 wh plug in ....
May 24, 2016

Maths
let that time be n years 1.02^n = 2 log both sides, then use rules of logs n log1.02 = log2 n = log2/log1.02 etc
May 24, 2016

algebra
generally called an inverse proportion ? then ... y = k/x if x = 2 , y = 12 12 = k/2 k = 24 y = 24/x
May 24, 2016

  1. Pages:
  2. <<Prev
  3. 1
  4. 2
  5. 3
  6. 4
  7. 5
  8. 6
  9. 7
  10. 8
  11. 9
  12. 10
  13. 11
  14. 12
  15. 13
  16. 14
  17. 15
  18. Next>>