Friday

July 29, 2016
Total # Posts: 35,362

**Error - Geometry**

This question makes no sense. You don't have a right-angled triangle , since 6^2 + 4^2 ≠ 7^2 from sinA = 6/7 , A = appr 59° from cosA = 4/7, A = appr 55° Which one is it ?
*April 29, 2016*

**math**

avg vel = total distance / total time find the time from 2:00 pm to 5:45 pm, write it as a decimal and go for it.
*April 28, 2016*

**Algebra**

ummmhh, if the points don't form a straight line, then the function is not linear.
*April 28, 2016*

**math**

I don't see any choices. y = 2x^3 - 4x + 1 dy/dx = 6x^2 - 4 at x = -1, dy/dx = 6-4 = 2 y = -2 + 4+1 = 3 so we have slope = 2, point is (-1,3) equation of tangent: y - 3 = 2(x + 1) dress it up to whatever form you need.
*April 28, 2016*

**math**

those codes don't work here, I read that as: C(x) = x^2 + 2 R(x) = 2x^2 - x equate them: 2x^2 - x = x^2 + 2 x^2 - x - 2 = 0 (x-2)(x+1) = 0 x = 2 or x = -1 if x=2, y = 6 if x = -1, y = 3 you had (2,-6) , don't see how you got y = -6 C(x) can never be negative, you are ...
*April 28, 2016*

**geometry**

Assuming that the peak of the house is in the centre of the width. tanØ = 40/15 = 8/3 Ø = appr 69°
*April 28, 2016*

**Math**

since both are expressed as y = ... we can equate them: x^2 + 2x = 3x + 20 x^2 - x - 20 = 0 (x-5)(x+4) = 0 x = 5 or x = -4 if x = 5, y = 3(5) + 20 = 35 if x = -4, y = 3(-4) + 20 = 8 x=5, y = 35 x = -4, y = 8 check: http://www.wolframalpha.com/input/?i=solve+y%3Dx%5E2%2B2x,++y%...
*April 28, 2016*

**Alias robert**

a = 2 v = 2t + c, where t is in seconds when t=0, v = 0 , (it started from rest) 0 = 0 + c, c = 0 v = 2t s = t^2 + k when t = 0, s = 0 , (hasn't gone anywhere) after 10 seconds v = 20 m/s s = 100 m now goes for 20 s, at 20 m/s, covering 400 m so it can covered 500 m, and ...
*April 28, 2016*

**Algebra**

In a multiplication of a number and a variable, we write the variable last, so Cost = 2a + 4c
*April 28, 2016*

**math**

done, look back at your other post
*April 28, 2016*

**math**

Assuming people are sitting on the ice while the Rangers are losing, .... area = π(202)^2 ft^2 = 40,804π ft^2 number of square ft per spectator = 40804π/20234 = appr 6.34 ft^2
*April 28, 2016*

**Math**

let the original amount be x he spent 3x/8, leaving him with 5x/8 he spends half of that , leaving him with 5x/16 5x/16 = 6.25 5x = 100 x = 20 He started with $20.00 check: he spends (3/8)(20) or $7.50, leaving him with $12.50 He has 1/2 of that left or (1/2)(12.50) = $6.25 My...
*April 28, 2016*

**math**

no, you have to use trig, or else know that the ratio of sides of the 30-60-90 triangle is 1:√3:2 So if the short side is 2, the sides are: 2 : 2√3 : 4 or make a sketch, mark the shortest side adjacent to the 60° angle as 2 and the hypotenuse as h cos60° = ...
*April 28, 2016*

**Math**

The product of distance x mass on both sides of the fulcrum must be the same, so 100d1 = 10d2 10d1 = d2
*April 28, 2016*

**centimeter dot grid**

Here is page full of printable graphpaper, many of which are metric. https://images.search.yahoo.com/search/images;_ylt=AwrB8qEruSJXTCoAA2KJzbkF;_ylu=X3oDMTBsZ29xY3ZzBHNlYwNzZWFyY2gEc2xrA2J1dHRvbg--;_ylc=...
*April 28, 2016*

**Math**

integral 10x/(x^2 + 1) dx from 0 to 5 = 5ln(x^2 + 1) | from 0 to 5 = 5ln 26 - 5ln1 = 5 ln 26 - 0 = 5 ln 26
*April 28, 2016*

**math**

PV = ?? Amount = 12500 i = .12/4 = .03 n = 4(12) = 48 PV(1.03)^48 = 12500 PV = 12500/1.03^48 = 3,024.99
*April 28, 2016*

**Plz do help..GEOMETRIC SEQUENCES**

You are looking at a GS with a = 32000 r = 1.04 term(n) = a r^(-1) term(n) = 32000(1.04)^(n-1) 32000(1.04)^(n-1) = 40000 1.04^(n-1) = 1.25 take logs of both sides and use log rules (n-1)log1.04 = log1.25 n-1 = log1.25/log1.04 = 5.689 n = 6.689 The question does not say when ...
*April 28, 2016*

**Algebra**

brackets are essential here don't you want to say x ≠ instead of x = ??? A 1/(6-x) , x ≠ 0,6 2nd one: 5(7+x) , x ≠0,-7 ----> choice A
*April 28, 2016*

**Math**

length = area/width = (2/3) / (1/2) = (2/3)(2/1) = 4/3 km check area = (4/3)(1/2) = 4/6 = 2/3 all is good
*April 28, 2016*

**,math**

let y = x^2 + 10x + 12 = (x^2 + 10x + 25 - 25) + 12 = ( (x+5)^2 - 25) + 12 = (x+5)^2) - 25 + 12 = (x+5)^2 - 13 we have found the vertex to be (-5,-13), which for a parabola would be the turning point.
*April 28, 2016*

**maths**

number of children -- c number of sweets per child -- s sc = 60 or c = 60/s 2nd scenario: number of sweets per child = s-1 (s-1)(c+2) = 60 sc+ 2s - c - 2 = 60 60 + 2s - c - 2 = 60 2s - c = 2 2s - 60/s = 2 2s^2 - 60 = 2s s^2 - s - 30 = 0 (s+5)(s-6) = 0 s = 6 or s is a negative ...
*April 28, 2016*

**8th grade math - system of equations**

#23 The larger number is three more than the smaller ---- l = s + 3 you had "the larger is 3 times the smaller" l - s = 3 l + s = 27 add them 2l = 30 l = 15 and 15+s= 27 s = 12 24. 5% ---> .05, so .05x + .09y = 380 multiply by 100 5x + 9y = 38000 ** first equation...
*April 27, 2016*

**algebra**

larger x smaller y x+y = 83 x - 3y = 19 subtract them: 4y = 64 y = 16 , then x = 67 larger is 67, the smaller is 16
*April 27, 2016*

**matc**

The $5,500 is irrelevant, all you want is the annual rate equivalent to 6% per annum, compounded monthly let that annual rate be i 1+i = (1 + .06/12)^12 1+i = 1.005^12 = appr 1.06168 the equivalent annual rate is 6.168 %
*April 27, 2016*

**algebra, how to do fractions?**

Don't let the fractions scare you .... slope = (15/32 - 1/4)/(5/8 - 1/3) = (15/32 - 8/32)/(15/24 - 8/24) = (7/32) / (7/24) = (7/32)(24/7) = 3/4 so y - 15/32 = (3/4)(x - 5/8) y - 15/32 = (3/4)x - 15/32 times 32 32y - 15 = 24x - 15 24x - 32y = 0 3x - 4y = 0
*April 27, 2016*

**math**

1(1.045)^n = 3, where n is the number of half-years. using logs ... n log 1.045 = log 3 n = log3/log1.045 = 24.95888 or 25 half-years. I would say 12.5 years.
*April 27, 2016*

**PreCalc**

when t=0 , temp = 35 when t = 12, temp = 50 Period = 24 hours or k = π/12 how about Temp = 7.5cos (π/12)(t + 12) + 42.5 check: when t = 0, Temp = 7.5cos(π) + 42.5 = 35 when t = 12, Temp = 7.5cos(2π) + 42.5 = 50 You try it with a sine curve, be aware that ...
*April 27, 2016*

**prealgebra**

#1, ok #2 .245 = 24.5% , move decimal 2 places to right, tag on the % sign #3 28% = .28 = 28/100 = 7/25, so C #4 .367 -----> .367 36.5% --- > .365 9/25 -----> .36 so what do you think?
*April 27, 2016*

**Probability**

prob = (18/30)(17/29) = 51/145 = appr .352
*April 27, 2016*

**MATH PLS HELP**

I can't quite see your work for this assignment.
*April 27, 2016*

**Trig**

h/23 = tan 40 h = 23tan40 = ....
*April 27, 2016*

**Math**

Logy=1/3(logx-log27) logy = 1/3 log (x/27) log y = log (x/27)^(1/3) antilog it y = (x/27)^(1/3) or y = (1/3)x^(1/3)
*April 27, 2016*

**math**

Just translate it to Math 2(x+7) < x by 19 2x + 14 = x-19 x = -33 check: add 7 to -33 ---> -26 double it -----> -52 19 less than the number = -33-19 = -52 YEAH
*April 27, 2016*

**math**

a = 1.6 b = 2 c = 2.5 x = (-b ± √(b^2 - 4ac)/(2a) (you MUST memorize this formula) x = (-2 ± (√(4 - 4(1.6)(2.5))/3.2 = (-2 ± √-12)/3.2 This is a complex or imaginary number, so there is no REAL solution. Is that your problem? Have you ...
*April 27, 2016*

**pre-calculus**

so arccos(?) is an angle, so let arcos(x/2) = θ that means cosθ = x/2 that is cosθ = adjacent / hypoenuse = x/2 so we are looking at a right-angles triangle with angle θ, adjacent = x, hypotenuse =2 Make a sketch, then x^2 + y^2 = 4 y^2 = 4-x^2 y = √(...
*April 27, 2016*

**Math**

let the initial population be 1 or 100% after 10 years: pop= 1(2)^(-10/7) = .3715 or 37.15%
*April 27, 2016*

**Help Steve or Damon, Solid Mensuration**

Am I overthinking this ???? volume of water in cylinder being upright = π(2^2)(41/12) inches^3 , (arrhhhg -- non-metric units) = (41/3)π in^3 Now lay it on its side, and make a diagram of the cross section Shade in the water which is a segment of the circle, label ...
*April 27, 2016*

**calculus**

How does this question relate to your two previous questions, let's see.... Let the base be x by x inches, and the height be y inches V= x^2 y 27 = x^2 y y = 27/x^2 material = 2x^2 + 4xy = 2x^2 + 4x(27/x^2) = 2x^2 + 108/x d(material)/dx = 4x - 108/x^2 = 0 for a min/max of ...
*April 27, 2016*

**calculus**

see my previous reply to this same idea.
*April 27, 2016*

**calculus**

width --- x length -- y 2x+2y = 320 y = 160-x area = xy = x(160-x) = -x^2 + 160x this is a downwards opening parabola with a vertex at (80, 6400) (I assume you know how to find the vertex) the max area is 644 m^2 , when x = 80m that is, when the rectangle is a square, which ...
*April 27, 2016*

**Math**

After giving to his son, he has 3x/8 left after giving to his daughter he has 3x/16 left 3x/16 = 150 3x = 2400 x = 800 check: first gift = (5/8)(800) = 500 amount left = 300 2nd gift = (1/2)(300) = 150 amount left = 150 Editorial: Looks like sexism in continued in math ...
*April 27, 2016*

**algebra**

width --- y length --- 3y area = y(3y) or 3y^2
*April 27, 2016*

**math**

most scientific calculators have the ! function built in on mine I press: 5 2ndF 4 -----> on mine the ! is with the 4 key = 120
*April 27, 2016*

**Maths**

x = 2cos t y = 2sin t dx/dt = -2sin t dy/dt = 2cos t slope = dy/dx = (dy/dt) / )dx/dt) = 2cost/-2sint = -cost/sint when t = pi/6 sint = 1/2 cost= √3/2 slope = (-√3/2)/(1/2) = -√3 point: (2cos pi/6, 2sin pi/6) or (√3 , 1) So now you have m = -√3, ...
*April 27, 2016*

**algebra**

let the first 4 terms of the AP be a-d, a , a+d, and a+2d new sequence is a-d+1, a+2, a+d + 7, and a+2d+20 so (a+2)/(a-d+1) = (a+d+7)/(a+2) (a+2)^2 = (a-d+1)(a+d+7) a^2+4a+4 = a^2+ad+7a-ad-d^2-7d+7a+d+7 -4a = -d^2 - 6d + 3 4a = d^2 + 6d - 3 ** (a+d+7)/(a+2) = (a+2d+20)/(a+d+7...
*April 27, 2016*

**maths**

I will assume you meant: 3 log9 9^2 = 6 log9 9 = 6(1) = 6
*April 27, 2016*

**maths**

did you mean: log √(x+1) + 9logx ?? then = log √(x+1) + log x^9 = log ( x^9 √(x+1) )
*April 27, 2016*

**maths**

I will assume you meant: log(x^2 y^3) then: = log x^2 + log y^3 = 2logx + 3logy = .... take over
*April 27, 2016*

**math**

y + 2x - 12 = 0 or y = -2x + 12 has a y-intercept of 12 5x + 12y = 8 has a slope of -5/12 so your new line is y = (-5/12)x + 12
*April 27, 2016*

**math**

Interest = 100,000(.06)(30) = 180,000 (This is a completely meaningless answer. Nobody would charge simple interest for such a period of time. The formula assumes that there is always 100,000 owing, but aren't there payments made in a "house loan", generally ...
*April 26, 2016*

**PreCal**

I am missing the speed of the wind.
*April 26, 2016*

**PRECALC**

#1, look how I did this similar problem, and follow the same steps http://www.jiskha.com/display.cgi?id=1461697741 #2 2 cos(θ) tan(θ) + tan(θ) = 1 + 2 cos(θ) 2cosθtanθ - 2cos + tanθ - 1 = 0 2cosθ(tanθ - 1) + (tanθ -1) = 0 by ...
*April 26, 2016*

**mathh**

y - 67/36 = (1/4)(x - 4/9) expand, then multiply each term by 36, the LCD
*April 26, 2016*

**precalc**

square both sides cos^2 x + 2sinxcosx + sin^2 x = 1 1 + 2sinxcosx = 1 sin (2x) = 0 2x = 0 or 2x = π or 2x = 2π x = 0, x = π/2, x = π the period of sin 2x is π, so adding multiples of π will yield more answers so in the domain 0 < x < 2π...
*April 26, 2016*

**Calculus**

let the height of the water be h m let the radius of the water level be r m Make a sketch of the cross-section. By similar triangles: r/h = 40/10 r = 4h or h = r/4 V = (1/3)π r^2 h = (1/3)π(4h)^2 h = (16/3)π h^3 dV/dt = 16π h^2 dh/dt plug in the given ...
*April 26, 2016*

**Math**

What is 22,000(.94)^6 ??
*April 26, 2016*

**Calculus**

V = (4/3)πr^3 dV/dt = 4πr^2 dr/dt when r = 5 and dr/dt = 2 dV/dt = 4π(25)(2) = 200π cm^3/min SA = 4πr^2 d(SA)/dt = 8πr dr/dt = 8π(5)(2) = 80π cm^2/min
*April 26, 2016*

**Geometry**

Remember that for each chord , a perpendicular from the centre will right-bisect the chord so if you let the height to the shorter chord be h1, and the height form the centre to the longer chord be h2 you have two right-angled triangles, the first one sides 6, h1, and ...
*April 26, 2016*

**maths**

Look carefully, Damon had .75 not 75 45 minutes = 3/4 hour = .75 hours
*April 26, 2016*

**Mathematics**

number of boys --- x number of girls --- x+36 x/(x+36) = 2/5 5x = 2x + 72 3x = 72 x = 24 so we have 24 boys and 60 girls for a total of 84 adults/children = 5/6 adults/84 = 5/6 6adults = 420 adults = 70 All is known
*April 25, 2016*

**Math**

Prob = (1/2)(1/2)(1/2) = 1/8
*April 25, 2016*

**Math**

Since we can only add "like" terms, wouldn't we have to add x^3 + 5x^3 ?? And that would give us ..... ?
*April 25, 2016*

**Math PLZZZ HELP ME!!!!!**

look back at your previous post of this question.
*April 25, 2016*

**Algebra**

x^2+6x=-7 x^2 + 6x + 9 = -7+ 9 (x+3)^2 = 2 x+3 = ± √2 x = -3 ± √2
*April 25, 2016*

**Math**

The mathematical probability of rolling a 5 on a die is 1/6 so the number of times you would get a 5 in 300 rolls = (1/6)(300) = 50 so your "experimental" probability had to be different from the mathematical one. And you didn't state the experiment, so I can'...
*April 25, 2016*

**Math**

Let me try to wade through this quagmire of a sentence. A four digit decimal number lies between 10 and 20. ---> 1x.yz My tenths digit is twice my tens digit. ---> 1x.2z The sum of my tenths and my ones digit equals my hundredth digit. ---> 2+x=z ** The sum of all my ...
*April 25, 2016*

**Math(Quadratic Functions)**

For days ???? since the x-intercepts of a function are the same as the roots of the corresponding equation x=7 ----> a factor of (x-7) x=-2 ---> a factor of (x+2) so f(x) = a(x-7)(x+2) we are told that (0,5) lies on it, so 5 = a(-7)(2) a = -5/14 f(x) = (-5/14)(x-7)(x+2) ...
*April 25, 2016*

**Roots, complex numbers**

This question must be a popular one. Did it yesterday http://www.jiskha.com/display.cgi?id=1461490844
*April 25, 2016*

**Math**

A = 800(3)^3.12 = appr 24644 bacteria
*April 25, 2016*

**Math**

90000 = 45000(1.075)^n 2 = 1.075^n log both sides log 2 = nlog1.075 n = log2/log1.075 = appr 8.58 years
*April 25, 2016*

**Calculus**

let the height along the wall be y m let the distance from the wall along the ground be x x^2 + y^2 = 6^2 2x dx/dt + 2y dy/dt = 0 x dx/dt + y dy/dt = 0 when x = 4 16 + y^2 = 36 y = √20 , and dx/dt = 1 4(1) + √20 dy/dt = 0 dy/dt = -4/√20 m/sec the negative ...
*April 25, 2016*

**algebra 2**

see this similar question http://www.jiskha.com/display.cgi?id=1461613740
*April 25, 2016*

**algebra 2**

see this similar question http://www.jiskha.com/display.cgi?id=1461613740
*April 25, 2016*

**math**

volume = πr^2 h = π(25)(10) cm^3 = appr 785.4 cm^3 by the beauty of the metric system, that would be .7854 kg of water so the empty container weighs 2 - .7854 or aprr 1.21 kg
*April 25, 2016*

**algebra 2**

follow the same steps I just showed you in your previous post
*April 25, 2016*

**algebra 2**

you will need to find the vertex of this parabola, a) and c) can then be answered the t of the vertex is -b/(2a) = -64/-32 = 2 s(2) -16(4) + 64(2) + 80 = 144 the vertex is (2,144), what does that vertex tell you? b) when it reaches the ground, s = 0 -16t^2 + 64t + 80 = 0 ...
*April 25, 2016*

**Math/Precsl**

log(8y+12)=2 <-----> 8y + 12 = 10^2 8y = 88 y = 11
*April 25, 2016*

**math**

number of 100 rupee winners ---- x number of 25 rupee winners --- 63-x 100x + 25(63-x) = 3000 100x + 1575 - 25x = 3000 75x = 1425 x = 19 state your conclusion
*April 25, 2016*

**Math**

amount at 3% --- x amount at 8% --- 9000-x .03x + .08(9000-x) = 580 solve for x
*April 25, 2016*

**geometric sequences**

to find r, (90/17) / 9 = 10/17 and (900/289) / (90/17) = 10/17 a = 9 r = 10/17 term(n) = 9(10/17)^(n-1) term(10) = 9(10/17)^9 = appr .07589
*April 25, 2016*

**Math/precal**

for the y-intercept, let x = 0 y = 7b^0 = 7 for the x-intercept, let y = 0 0 = 7b^x no solution for x (normally we would take the log of both sides, but we can't take log0)
*April 25, 2016*

**Maths**

a + ar = 9 a(1+r) = 9 a = 9/(1+r) a/(1-r) = 12 a = 12(1-r) 12(1-r) = 9/(1+r) 1 - r^2 = 3/4 4 - r^2 = 3 -r^2 = -1 r = ± 1
*April 25, 2016*

**maths**

Just add them, the 1/y's will drop out 2/x = 6 6x = 2 x = 1/3 sub into the original first 1/y + 1/(1/3) = 5 1/y + 3 = 5 1/y = 2 y = 1/2
*April 25, 2016*

**Math**

For the volume I got 538.8 ft^3 to the nearest tenth of a foot. (you should really use a better value for π than 3.14, most calculators have it built in correct to 10 decimals) Your SA is made up of 2 circles + a rectangle SA = 2π(3.5)^2 + 2π(3.5) = 384.8 ft^2
*April 25, 2016*

**Algebra**

Where does the 4 come from? There are 36 cookies in 6 bags, so the number of cookies in each bag = 36/6 = 6
*April 25, 2016*

**Calculus**

let the length of line be L ft let the horizontal distance of the boat from the dock be x ft You have a right-angled triangle, thus x^2 + 3^2 = L^2 2x dx/dt = 2L dL/dt for the given case: x = 4 L^2 = 4^2 + 3^2 L = 5 2(4)(7) = 2L dL/dt dL/dt = 2(5)/(56) = 5/28 ft/s
*April 25, 2016*

**MATH**

What am I missing here? Isn't the circumference of the cylinder simply the circumference of the circle? which would be 3.2π inches. The height of 8 inches would have nothing to do with it.
*April 25, 2016*

**Math**

volume of cubes is proportioanl to the cube of their corresponding sides so V/729 = 4^3/3^3 27V = 46656 V = 1728 notice the sides increased by a ratio of 4:3 and 1728/729 = 64/27 = 4^3 : 3^3
*April 25, 2016*

**Algebra**

Ok, multiply the first by 4, then subtract the 2nd multiply the first by 3, then subtract the third. Now you have two equations with y's and z's carry on
*April 25, 2016*

**Algebra**

Why eliminate x when the obvious choice would be to eliminate z ?? #2 - #1 ---> 3x - 4y = 1 ** #2 - #3 ---> x - y = 2 or x = y+2 sub that into ** 3(y+2) - 4y = 1 3y + 6 - 4y = 1 -y = -5 y = 5 , then x = 7 back into #1: 7 + 5 + 5z = 2 5z = -10 z = -2 so the solution is (7...
*April 25, 2016*

**Maths**

2nd term = a+d 7th term = a+6d a+d + a+6d = 20 2a + 7d = 20 ** (a+d)/(a+6d) = 1/3 3a + 3d = a + 6d 2a = 3d *** sub that into ** 3d + 7d = 20 10d = 20 d = 2 then 2a = 6 a = 3 "Calculate The Sum Of The 1st Terms Of The G.P" HUH? I thought we were dealing with an AP. ...
*April 25, 2016*

**algebra**

short leg --- x longer leg --- x+2 x^2 + (x+2)^2 = 8^2 x^2 + x^2 + 4x + 4 - 64 = 0 2x^2 + 4x - 60 = 0 x^2 + 2x - 30 = 0 let's complete the square: x^2 + 2x + 1 = 30+1 = 31 (x+1)^2 = 31 x+1 = ± √31 x = -1 ± √31 but x has to be positive, so x = &#...
*April 24, 2016*

**Math**

take 1/2 of the -7 and square that so (-7/2)^2 = 49/4 we should add 49/4 to both sides
*April 24, 2016*

**Math**

herding my way through that first "sentence" .... I got the obvious: h = -16t^2 + 96t + 3 a) plug in t = 0 b) find the vertex and both b) and c) are answered.
*April 24, 2016*

**Math**

what is 7! ?
*April 24, 2016*

**Math**

That's a lot of fencing.. No diagram can be used in this format. Check your post for typos and grammar before posting.
*April 24, 2016*

**Math**

3 -> 9 5 -> 25 2 -> ? 7 -> 49 if x is input and y is output, it sure looks like y = x^2
*April 24, 2016*

**Math**

prob(all 4 boys) = (1/4)^4 = 1/256 = .... you do the button-pushing
*April 24, 2016*

**Algebra 1**

No, your choice is not correct It is B If I multiply the first equation by -2, don't I get the 2nd equation??? So one is a multiple of the other.
*April 24, 2016*