Wednesday
July 30, 2014

Posts by Reiny


Total # Posts: 26,923

math
just evaluate y for the given x's and plot the points e.g , when x = -2 y = (1/3)(2) - 2 = 2/3 - 2 = -4/3 ------> so you have the point (-2, - 4/3

math
Actually I just noticed your equation is not quite clear. is the exponent 3 ? then you would have written it as y = 2x^3 or did you forget to type the exponent ? It would be highly unusual for a text to put the + sign in front of the exponent like you typed it.

math
evaluate the y for the given x's, then plot the points. Join them with a smooth curve. You will get a parabola

Math
Assuming your ã is √ #3 , the -11√8 becomes -22√2 the rest are correct

alegbra/stressed
in each case you divide the rate by the annual compounding frequence, and multiply the years by that annual compouding frequency e.g. if compounded quarterly, the annual compounding frequencey is 4 I will do that one, you try the others. 6.9 %> compounded quarterly i = .069...

Math
I think we should use compound interest here. i = .09/12 = .0075 let the payment be p p( 1 - 1.0075^-36)/.0075 = 100000 p = $3179.97

Chemistry, not Math
label your problem using the right subject

math
for the 1st pair, since you know what y is , just plug that value into the first equation and solve for x #2: 3x - 14y = 0 x - 4y + 1 = 0 3x - 14y = 0 multiply the 2nd by 3 3x - 12y = -3 subtract them -2y = 3 y = -3/2 sub into x - 4y = -1 x - 4(-3/2) = -1 x + 6 = -1 x = -7 x =...

math
4(2x-9)-4x= 4-6x 8x - 36 - 4x = 4 - 6x 10x = 40 x = 4 16y plus 4 =-10 16y + 4 = -10 Does your keyboard not have a + sign? 16y = -14 y = -14/16 = -7/8

Math
it is called a subscript it is not an actual mathematical operator, but instead is an indicator. e.g. you often see it to label two points (x1 , y1) and (x2 , y2) to state that you have two points of the form (x,y) but the x's and y's are different e.g. if you have two...

maths
What does "works up to" mean in mathematics ????

Math
942!/(15n) = 942x941x940x939x938!/(15n) = 942(941)(188)(313)(938!)/n I divided by 5 and by 3 leaving the division by n

Math
multiply top and bottom by √6 + √3 (2 √ 6 + √ 3)/ ( √ 6- √ 3) * (√6 + √3)/(√6 + √3) = ( 12 + 3√18 + 3)/(6-3) = (15 + 9√3)/3 = 5 + 3√2

Calc Help Please Again Last one!
I will split it up for you ... (6x-58)/( (x+9)(x-7) ) let A/(x+9) + B/(x-7) = (6x-58)/( (x+9)(x-7) ) A(x-7) + B(x+9) = 6x - 58 let x = 7 0 + 16B = -16 B = -1 let x = -9 -16A + 0 = -112 A = -7 so .... (6x-58)/( (x+9)(x-7) ) = -7/(x+9) - 1/(x-7) now it integrates easily using ln...

Calc Help Please Again!
can't tell if your equation is y = e^(x+4) or y = e^x + 4 , why is there a 1 in front of the x ?

Calc Help Please
I got (1/4) (ln(x-2) - ln(x+2) ) + c how did your x-2 from the original denominator turn into 2-x) I used partial fractions

Geometry
make a sketch to see that height/36 = tan 25° height = 36tan25 = appr 16.8 ft

Algebra
yes

alegbra
my equation, (very close to yours) 225500 = PV e^(8.4246575(.0855)) 225500 = PV e^(.720308219) , now press 2nd ln 225500 = PV (2.055066524) PV = 109,728.81 I let the calculator carry all the decimal places and only rounded off my final answer to the nearest cent. You were off ...

math
distance = √( (-3-8)^2 + (-10+10)^2) = √(121 +0) = √121 = 11 We can see this without any calculation. Since the x values are the same for both points, the line is a vertical one. So all we have to do is take the difference between -3 and 8 , which is 11

math
number of $5 tickets --- x number of $10 tickets --- y number of $15 tickets ---- 180-x-y x + (180-x-y) = 2y x + 180 - x - y = 2y 180=3y y = 60 income equation: 5x + 10y + 15(180-x-y) = 1900 5x + 600 + 15(120-x) = 1900 5x - 15x + 600 + 1800 = 1900 -10x = -500 x = 50 x=50 y=60 ...

math(compound interest )
What you wanted as an equation is ... [ x( 1 + .1/360)^20 - 600 ](1+.1/360)^108 = 8900 x(1+.1/360)^20(1+.1/360)^108 - 600(1+.1/360)^108 = 8900 x((1.00557024)((1.03045024) - 618.2701442 = 8900 x(1.036190095 = 9518.270144 x = 9185.83

math trigonometry
I don't understand your question. Are we looking at two different equations ? Are we solving 10 sec Ø + 13sinØ = 0 and 5tan Ø - 12 = 0 ???? or .... ? is (0,90°) the domain?

Algebra 1
first equation: -2x - 2y = 4 ----> x+y = -2 2nd equation: 2y = -2x - 4 2x + 2y = -4 x + y = -2 looks like they are the same line, so you have one line any ordered pair that works in one of them, will work in the other. There will be an infinite number of solutions.

Math-- Ms. Sue??
#1 , wrong. If you plot your points you will see that it is (8,5) notice that now two pairs of points have the same x , making the lines vertical, and 2 pairs of points have the same y, making the horizontal. #2, ok #3, ok #4, your answer: (5,-4) and (-2,1) -- slope = (1-(-4))...

Math
prob(brown, then violet) = (8/16)(1/16) = 1/32

Math - Int Trig
y = √x shift up 4 units -----> y = √x + 4 reflect about the y-axis ---> y = √-x + 4 , for x ≤ 0 shift right 2 units -----> y = √(-(x-2)) + 4 , x≤2 again, Wolfram verifies this http://www.wolframalpha.com/input/?i=y+%3D+√%28-%2...

Math - Int Trig
start: y = |x| shifted right : y = |x-3) stretched by factor of 3 : y = 3|x-3| vertically down 2: y = 3|x-3| - 2 reflected about x-axis y = -3|x-3| + 2 behold the wonders of Wolfram http://www.wolframalpha.com/input/?i=y+%3D+%7Cx%7C+%2C+y+%3D+%7Cx-3%7C+%2C+y+%3D+3%7Cx-3%7C+%2C...

math
multiply each of the prob. answers I just gave you by 100

math
Four possible outcomes: HH HT TH TT prob(HH) = 1/4 prob(TT) = 1/4 prob (TH or HT) = 2/4 = 1/2 notice the 3 answers add up to 1, since one of those possibilities must happen

Geometry
(-3,-1) ---- dilation factor of 2 ----> (-6, -2) show it by plotting the two points how does the distance to the origin change ?

Algebra 1
looks like f(3) = 2 then g( f(3) ) = g(2) = -3

Trig 3
sloppy way of writing the trig expressions ( when you write tan2, you are asking for the tan(2 radians. What you meant was something like tan^2 Ø It has to be the sine of something, the cosine of something, or the tangent of something. anyway ..... (1 - cos^2 Ø)/...

Geometry
Any regular n-gon can be changed to n isosceles congruent triangles by drawing all radii to the vertices of the polygon. the area of a triangle = (1/2)(base)(height) the area of one of these = (1/2)(side)(apothem) where the apothem is the distance from the centre of the polygo...

math(compund interest )
Major Hint: Did you notice that from 16 April to 16 Oct is 6 months? So your time can be very easily expressed in half-years, and quarter-years. From all the knowledge you have gained by having received many answers for similar questions to the above, you should now be able to...

mathematics for management
NO you used the concept of continuous compounding but it said it was compounded monthly Even with the above in consideration your expression of 8888(e^0.06(0.25)) makes absolutely no sense. i = .06/12 = .005 n = 3(12) = 36 months PV = 8888(1.005)^-36 = $7427.21 For a single in...

math
How do you expect us to know what table you are working from. With today's excellent scientific calculators, the use of "tables" that were found in the back of most textbooks in the past is no longer common practise. Your question is simply PV = 100000(1.05)^-50 ...

math
what is 20000(1.06)^15 ?

math(urgent)
Just use the formula. Amount = payment( (1+i)^n -1)/i Amount = 1000(1.08)^3 -1)/.08 = 3246.40

Trig
3x^2 + 4y^2 = 12 divide by 12 x^2/4 + y^2/3 = 1 we know sin^2 t + cos^2 t = 1 so sin^2 t = x^2/4 = (x/2)^2 ---> sin t x/s ----> x = 2sin t and cos^2 t = y^2/3 = (y/√3)^2 cos t = y/√3 ----> y = √3cos t x = 2sint y = √4cost confirmation: http://w...

Calculus
dy/dx = 2tan (x^4) * sec^2 (x^4) * 4x^3

ALGEBRA
using the ratios, let the width be 8x and the length be 15x led d be the diagonal d^2 = (8x)^2 + (15x)^2 = 64x^2 + 225x^2 = 289x^2 d = 17x or x = d/17 width = 8x = 8d/17 length = 15x = 15d/17

geometry
volume of similar solids is proportional to the cube of their corresponding sides so ratio of volume = 3^3 :^3 = 27 : 125

Math
so you want 9(2)(t/9) = 1000000 2^(t/9) = 111,111.111.. t/9 log2 = log111111.11 t/9 = log111111.11../log 2 = 16.7616.. t = 150.8548 years so 1909 + 150.8548 yrs = appr 2060 just what Ms Sue got by continuing her chart.

math
1.75 years = 21 months monthly rate = .18/12 = .015 PV = 900(1.015)^-21 = $658.35

math
100% of something = the whole thing or 1 50% of something = .5 or 1/2 of the whole thing = .5 145% of something = 1.45 yes, C is the right choice.

math (urgent )
my answer confirmed by Wolfram http://www.wolframalpha.com/input/?i=13.875-0.1875%2856.375%29%2F8-2+%281%2F8%2B27.125%2F300.875%29+

math (urgent )
This is what you typed: 13.875-0.1875(56.375)/8-2 (1/8+27.125/300.875 I added a bracket at the end, or else they are mismatched. Followed the order of operation, and got 12.1234035... The way you wrote it, there is now way to get 1.1908 check how you placed your brackets.

Geometry Help & Proofs
based on : ratio of volumes is proportional to the cube of their corresponding sides. so ratio of volumes: A : B = 1 : 5 A : C = 1^3 : 2^3 = 1 : 8 B : D = 1^3 : 3^3 = 1 : 27 A/B = 1/5 B = 5A A/C = 1/8 C = 8A B/D = 1/27 D = 27B ratio of volume of C :D = 8A : 27B = (8/27)(A/B) =...

Math
9/9 = 1 = 12/12 2/3 = 8/12 5/6 = 10/12 4/12 = 4/12 0/2 = 0 , obviously the smallest now can you tell ?

Algebra
(x - y) (3x + xy - 4y) + xy^2 - x^2y = (x-y)(3x + xy - 4y) - xy(x - y) = (x-y)(3x + xy - 4y - xy) = (x-y)(3x - 4y)

Math
The total of the first 16 students' marks was 16x66 or 1056 the total of the new students' marks was 6x74 or 444 so the total of the 22 students was 1500 giving an average of 1500/22 or appr 68.2

finance
WoW! I recognize the formula Future Value = Present Value (1 + i/n)^(cn) where n is the frequency of compounding per year and c is the number of years from your (1.089/12)12*5 I gather that the interest rate was 8.9 % per annum compounded monthly , for a time of 5 years and yo...

Algebra 1 Answer Evaluation
anything squared cannot be negative in the real number set, so your first one has no real number solution 2. correct

math
distance (d) ∝ time (t) d = kt case 1: when t = 2 , d = 90 90 = k(2) k = 45 so d = 45t , the constant of proportionality is 45 the unit rate is 45 mph check on the others t = 3 --> d = 45(3) = 135 ✔ t = 5 --> d = 45(5) = 225 ✔ t = 6 --> d = 45(6) =...

Algebra 1 (Reiny)
x^2 + 3x - 18 = 0 (x+6)(x-3) = 0 x = -6 or x = 3

MATH: TRIG
you should recognize the 3-4-5 right angled triangle. so if cosx = 3/5 then sinx = 4/5 sin 2x = 2sinxcosx = 2(4/5)(3/5) = 24/25 you can always check your result with a calculator.

Maths
use substitution x^2 + 3x - 5 = x-2 x^2 + 2x - 3 = 0 (x+3)(x-1) = 0 x = -3 or x = 1 check with Wolfram http://www.wolframalpha.com/input/?i=Y%3Dx-2+%2C+Y%3Dx%5E2%2B3x-5 if x = -3, y = -3-2 = -5 if x = 1 , y = 1-2 = -1 x=-3, y=-5 ---> point (-3,-5) x = 1 , y = -1 --->poin...

Algebra II
quick way: for any linear equation written in the form Ax + By + C = 0 the slope is -A/B so here, the slope is -6/5

math
Don't post the same question using different names please.

math
3+x/7+x= 3/7 + 3/7 I would multiply each term by 7 , the LCD 21 + x + 7x = 3+3 8x = -15 x = -18/8 I seriously suspect a typo

math
3(40+x) = (2+3)(3+4)(4+5) 120 + 3x = 5(7)(9) = 315 3x = 195 x = 65

geometry
He has not seen 5 of the comedies and 7 of the dramas Since you want the non-seens from one OR the other there are 12 movies he has not seen prob(nonseen) = 12/18 = 2/3

Algebra 1--Please, help me!
1. 4x^2 + 8x = 32 4x^2 + 8x - 32 = 0 x^2 + 2x - 8 = 0 let y = x^2 + 2x - 8 now graph this, and look at where it crosses the x-axis. From Wolfram's graph http://www.wolframalpha.com/input/?i=y+%3D+x%5E2+%2B+2x+-+8 we can see x = -4 or x = 2 2. x(x + 3) = 32 x^2 + 3x - 32 = ...

oops - MATH
just noticed an arithmetic error.. in my evaluation of y, should be 60 - 2x = 60-2(20) = 20 so ..... max profit is 30(20) + 50(20) or 1600 , when 20 of the first product and 20 of the second product are made

MATH
let the number of the first product be x let the number of the 2nd product by y So we need to look at the regions 2x+y ≤60 and x+y≤30 and x+3y≤80 The profit function is 30x+50y which has a slope of -3/5 move that profit line to the right, parallel to itself, ...

Math
I tried a slightly different approach I looked at the trapezoid, and drew two verticals upwards from the base, creating a rectangle of 25 by 50 cm and two right-angled triangles , each of height 50 and base 75/2 I drew a water line, of height h and width of r in each of the tr...

Math
You don't have an equation, so "solving" is the wrong instruction. are you expanding 2a(a^2 + 4a) ? then... = 2a^3 + 8a^2

algebra
I don't know what h=−16t<E> 6<E>+s is supposed to say, but I know that h = -16t^2 is the relation between t seconds and the distance fallen in feet Since we just want to find the distance, let's use h = 16t^2 when t = 3 h = 16(9) = 144 feet If this is...

Math
slope for the first 2 points = (0-1)/(4-2) = -1/2 y = -1/2 x + b , but (2,1) lies on it 1 = -(1/2)(2) + b b = 2 y = -(1/2)x + 2 check if third point is on it LS = -1 RS = (-1/2)(6) + 2 = -1 yes, all is good y = (-1/2)x + 2

Math
nothing to "solve", you don't have an equation. did you mean: evaluate 5(3^n) for n = 1,2,3, ... then you would get 5(3) , 5(9), 5(27), 5(81) .. = 15, 45, 135, 405, looks like that is what you are doing, if so, you are correct.

Math
First of all you have not defined x and y Secondly, 2(x+y) does not look like an area, it looks like the perimeter of the original rectangle. I will attempt it anyway: I drew a rectangle of length x and width y I then drew two lines, one parallel to the length, the other paral...

MATHHH
case1: no defence in 1st row - we can choose any 6 of the 8 players = C(8,6) = 28 case2: 1 defence - four ways to choose the defenseman, choose 5 from the remaining 8 = 4 x C( 8,5) = = 224 Case3 : 2 defense = C(4,2) x C(8,4) = 420 total = 28+224+420 = 672 for choosing the 6 bu...

Math
first do this: 4√6/√30 = 4/√5 now multiply top and bottom by √5 4/√5 * √5/√5 = 4√5/5

alegbra
first of all your "equation" makes no sense. LS = 25 RS = 1/25 25 ≠ 1/25 secondly , equations tend you have a variable in there somewhere, else it simply becomes a mathematical statement which is either true or false e.g. 2+3 = 4 --- false 1+1 = 2 ---- true re...

alegbra
amount = initial (.5)^(t/5730) .75 = 1 (.5)^(t/5730) log .75 = (t/5730) log .5 t/5730 = log .75/log .5 = .415... t = 2378.16 age is about 2400 years to the nearest century

math
The way the question stands, the "bottom" of the kite could be any length along the missing part of the diagonal. The angle at the shorter diagonal's end wasn't a right-angle ?

math
I think we are missing information Was there an angle given?

ALGEBRA
13.29 = 14.7 e^(.21a) .90408.. = e^(.21a) by rules of logs .21a = ln .90408... .21a = -.0100835.. a = -.48016 miles or - 2535 ft below sealevel !!!!!!! Wow, since the lowest point in North America, Death Valley is only about 260 ft below sea level, you city is a mystery. ... o...

Math
The surface area is proportional to the square of their radii (1.5r)^2/r^2 = x/36π 2.25/1 = x/36π x = 2.2(36π) = 81π

Math
From 1 to 10, isn't 6 the only number divisible by both 3 and 2 ? so prob = 1/10

math 7Probability help
mmmmmhhhhh possible sums of 2 dice is 2 , 3, 4, .... 11, 12, there are 11 of those the evens are: 2 4 6 8 10 12 or 6 of them so prob(even sum) = 6/11

Finance
I will do the last one, you do the other two in the same way c) PV = 5000(1.09)^-4 = $3542.13

Math
suppose we just look at 1/3^x (1/3^x - 2) = 15 3^-x(3^-x - 2) = 15 let 3^-x = a for easier typing then we have a(a-2) = 15 a^2 - 2a - 15 = 0 (a-5)(a+3) = 0 a = 5 or a = -3 3^-x = 5 log 3^-x = log5 -x log3 = log5 -x = log5/log3 x = -log5/log3 the other part of 3^-x = -3 has no ...

MATHHH
success if you draw 2 granolas or 2 fruits or 2 cheese prob(success) = (12/30)(12/30) + (10/30)(10/30) + (8/30)(8/30 = 4/25 + 1/9 + 16/225 = 77/225

maths
I will use a for alpha and b for beta then from the properties of zeros of a quadratic a+b = -1 ab = 1 then 1/a + 1/b = (b+a)/(ab) = -1/1 = -1 a^2 + b^2 = (a+b)^2 - 2ab = (-1)^2 - 2(1) = 1 - 2 = -1

Math
You could do the tedious task of expanding and then collecting powers of y^3. I let Wolfram do this for me http://www.wolframalpha.com/input/?i=expand+%281%2By%2Bky%5E2%29%5E7 It might be easier to read the expansion in reverse order 1 + 7y + 21y^2 + ... Notice that y^3 appear...

Calculus Please Help
What a mess! http://integrals.wolfram.com/index.jsp?expr=sqrt%28100x%5E2-400%29%2Fx&random=false add C to the result

Alegbra
I suspect that this is a log question and your IN is actually ln ( the natural logarithm) so let's try: t = -62.5 ln(1 - N/80) or is it t = -62.5 ln( (1-N)/80) look at the first of the Related Questions below. It is the same question and Steve had his doubts about the same...

Math
1^2-(2-x)^2=2^2-x^2 1 - (4 - 4x + x^2) = 4 - x^2 1 - 4 + 4x - x^2 = 4 - x^2 4x = 7 x = 7/4 I don't understand why a textbook would write a term as 1^2 and 2^2 in an equation. That is just silly.

Algebra (proportions)
let the number of bears be x 50/x = 2/100 2x = 5000 x = 2500

Calculus
y = u^3 + u^2 - 1 dy/du = 3u^2 + 2u u = 1/(1-x) = (1-x)^-1 du/dx = -1(1-x)^-2 (-1) = 1/(1-x)^2 when x = 2, u = 1/(1-2) = -1 du/dx = 1/(1-2)^2 = +1 dy/du = 3(-1)^2 + 2(-1) = 1 dy/dx = dy/du * du/dx = 1(1) = 1 check my arithmetic, I made several arithmetic errors tonight.

Math
It didn't, n = 0 became a solution. Are you not familiar that if you have a factored form = 0, such as (A)(B) = 0 , then A = 0 or B = 0 ???

Math
I took out a common factor of n expand n(1-2n) What do you get ?

Math
n(1 - 2n) = 0 n = 0 or 1 - 2n = 0 n = 0 or n = 1/2

Calculus
y= sqrt[(3x^2+2)^3] = (3x^2 + 2)^(3/2) dy/dx = (3/2)(3x^2 + 2)^(1/2) (6x) = 9x(3x^2+2)^(1/2) or = 9√(3x^2 + 2) , which is valid for all values of x since (3x^2 + 2) is always positive.

oops - Algebra
looks like I can't do a simple subtraction of course 50-32 = 18 as MathMate had

Algebra
let amount of stronger solution to be used be x L amount of weaker solution is 50-x L .8x + .3(50-x) = .62(50) .8x + 15 - .3x =31 .5x = 16 x = 16/.5 = 32 needs 32 L of the stronger and 36 of the weaker solution.

math
.48x = .35 x = .35/.48 = appr .73

Algebra
original width --- x original length --- y xy= 280 y = 280/x new width --- x+1 new length --- y-5 new area = (x+1)(y-5) = (x+1)(280/x - 5) = 280 - 5x + 280/x - 5 = 275 - 5x + 280/x = (275x - 5x^2 + 280)/x = -5( x^2 - 55x - 56)/x perfect squares in the neighbourhood of 280 are ...

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

Search
Members