Tuesday

May 3, 2016
Total # Posts: 40,130

**Geometric progression**

well, I gave you a hint. Try some synthetic division. You know that any rational roots must be found among ±1, ±1/2, ±2
*March 23, 2016*

**Geometric progression**

Geez, guy, you're not gonna work on it at all? a = 30(r-1)/(r^4-1) a = 18/(1+r^3) 30(r-1)(1+r^3) = 18(r^4-1) 30(r^4-r^3+r-1) = 18(r^4-1) 2r^4-5r^3+5r-2 = 0 I'll let you factor that and find that r=2 is a root.
*March 23, 2016*

**math**

too much water
*March 22, 2016*

**matematicas**

hace preguntas aqui
*March 22, 2016*

**Algebra**

it's just a fraction. x = -2/11 y = -5/11 That is the solution. Fractions are numbers, just like 5 and -12. No reason to be afraid of them. and that's should have read 3x+y=-1
*March 22, 2016*

**Algebra**

I assume you meant 3x+y = -1 So, 6x+2y = -2 But, 2y=5x, so 6x+5x = -2 now solve for x and then get y.
*March 22, 2016*

**Algebra**

well, you know that x = 8-2y so, substitute that into the other equation: 3(8-2y) - 4y = 4 Solve for y, then you can get x.
*March 22, 2016*

**Algebra**

if the width is w, then (20-2w)(24-2w) = 320
*March 22, 2016*

**Algebra**

group 1: 160 suits group 2: 3/4 * 160 = 120 suits If the 2nd team made x suits per day, then since it took 4 more days, 160/(x+10) + 4 = 120/x x = 10 extra credit: how many days did the teams work?
*March 22, 2016*

**Algebra**

this is the same as the other one. 150/(55+s) + 150/(55-s) = 11/2 s = 5
*March 22, 2016*

**Algebra**

Let x be the speed from A to B Since time = distance/speed, 120/x + 120/(x+10) = 240/x - 2/5 x = 50 km/hr
*March 22, 2016*

**Math**

(2x^3-9)/(x^3+6x^2+8x) = (2x^3-9) / (x)(x+2)(x+4) = 2 - (9/8)/x + (25/4)/(x+2) - (137/8)/(x+4)
*March 22, 2016*

**Math**

900900949 will round down to 900900900 anything larger will round up to 900901000
*March 22, 2016*

**maths**

if it is rectangular, the area is 1.5 * 3 = 4.5 m^2
*March 22, 2016*

**math**

It could be 5, but then it would be a square, and not really a trapezoid. Since three sides are all 5, it has two parallel sides of length 5. So, if you play around with some designs, you will see that forcing a 3rd side to be also 5, the figure can be low and flat, or square-...
*March 22, 2016*

**Math**

You are correct.
*March 22, 2016*

**math**

the width is 3 times as big, so the length is also.
*March 22, 2016*

**science help pls pls**

If it's a small lake, then all points nearby should have the same climate. If there are prevailing winds, then the spots downwind will be slightly cooler. Other than that, I have no advice to give. If it's a huge lake, I'd guess points at lower latitudes would be ...
*March 22, 2016*

**Math**

only straight line segments
*March 22, 2016*

**Math**

Thanks again😀
*March 22, 2016*

**Math**

She might draw out two of each color. There are only three colors, so on the 7th marble, it must be the same color as two of the others. So, with 7 marbles, she is sure to have 3 the same. How many of each color are in the box doesn't matter. Only the number of colors.
*March 22, 2016*

**Math**

I am having a problem answering this math problem. Andrea has a box of marbles in it. She has seven red marbles, thirteen blue marbles and nineteen yellow marbles. If she reaches in and takes out marbles without looking, what is the fewest number of marbles she will need to ...
*March 22, 2016*

**Math**

2 days is 48 hours, so 48/8 * 400 = 2400 mi
*March 22, 2016*

**Math**

try putting the LS over a common denominator: tanx/(1+secx) + (1+secx)/tanx tanx*tanx + (1+secx)^2 --------------------------- tanx(1+secx) tan^2x + 1 + 2tanx + sec^2x ------------------------------- tanx(1+secx) I ...
*March 22, 2016*

**math**

a(r^4-1)/(r-1) = 30 a + ar^3 = 18 a(1+r^3) = 18 it's easy to see that if a=2, r=2 Does that work on S4? 2*15/1 = 30. Yes So, the GP is 2,4,8,16,...
*March 22, 2016*

**stem and leaf plot**

got no data There are many graphers on line, such as http://www.calculatorsoup.com/calculators/statistics/stemleaf.php
*March 22, 2016*

**math**

That's better.
*March 22, 2016*

**math**

1/4 of 280 is 70 so, what is 3 times that? Did you just guess at 240?
*March 22, 2016*

**math**

recall the Pythagorean Theorem: 2^2 + h^2 = 10^2
*March 22, 2016*

**math**

7!/(3!2!2!) = 210
*March 22, 2016*

**math**

x/8 = cos68°
*March 22, 2016*

**Algebra**

since time = distance/speed, 480/s + 480/(s+20) = 20
*March 22, 2016*

**Algebra**

so? original fraction is x/(x+7) when changed, (x+3)/(x+7+5) = 1/2 2(x+3) = x+12 2x+6 = x+12 x = 6 original fraction is 6/13 new fraction is 9/18 = 1/2
*March 22, 2016*

**math**

The first question asked for a distance. You gave a time. The distance traveled is (4/5.25) * 273 = 208 miles
*March 22, 2016*

**geometry**

the area is A = bh/2 3h * h/2 = 6 3h^2 = 12 h^2 = 4 h = 2 b = 3h = 6 check: 2*6/2 = 6
*March 22, 2016*

**algrbra**

p+5n+10d+25q = 575 p+n+d+q = 40 Now you know that there are 5,7,11,13,17,19,23 as the number of each coin. Since there are no odd cents, you know that p=5. Now you have 5n+10d+25q = 570 n+d+q = 35 or, n+2d+5q = 114 n+d+q = 35 subtracting, we have d+4q = 79 4q must be 20,28,44,...
*March 22, 2016*

**math - Correction.**

On the first try, you were ok to here: y=(log7-log2)/log2 but that's y = log7log2 - 1 On the 2nd try, you went wrong right away: 3(2^y-1) is NOT 6^y-3 it IS 3*2^y - 3
*March 22, 2016*

**math**

why all the useless words? That's what math symbols are for! (8^(y+2)-34(2^(3y)))/√8^(2y+1) = (64*8^y - 34*8^y)/(√8 * 8^y) = 30*8^y / (√8 * 8^y) = 30/√8 = 15/√2 If I got the grouping wrong, fix it and redo the steps. But any other setup will ...
*March 22, 2016*

**math**

The interest would be 380 * .18 * 60/360
*March 22, 2016*

**Tokak**

If AB=8 and DC=5, then if the altitude is h, h = 4sinA = 6sinB h cotA + 5 + h cotB = 8 4 sinA cotA + 5 + 6 sinB cotB = 8 4cosA + 5 + 6cosB = 8 4cosA + 6cosB = 3 solve for A and B. Note that D = (90-A)+90 = 180-A and similarly for C.
*March 22, 2016*

**Maths**

max=10 for 10,20,...,90 min: 19/10 = 1.9
*March 22, 2016*

**Math**

outside: 2(3 2/3 + 4 1/2) = 16 1/3 ft inside (subtract 1/2 ft on each of the 4 sides): 16t 1/3 - 2 = 14 1/3 ft
*March 22, 2016*

**maths geomentry help!!!**

If the angle is x radians, 1/2 r^2 x = 20 2r + rx = 26 now just solve for r and x.
*March 22, 2016*

**Ouch! @DrBob**

ouch. You are correct. Dunno what I was thinking.
*March 21, 2016*

**Chemistry**

that gives you mol/cm^3 adjust for 1dm = 10cm
*March 21, 2016*

**calc**

weight: w(t) = 500+6t cost: c(t) = 0.50t price: p(t) = 1.00 - 0.01t sales profit per cow: s(t) = w(t)*p(t)-c(t) s(t) = (500+6t)(1-t/100)- t/2 You can ignore the number of head; that's just a constant multiplier. s(t) is just a parabola, so find the vertex for maximum profit.
*March 21, 2016*

**Math**

If there were x pencils sold the 1st day and y sold the 2nd day, x + y = 24 2x + 5/2 y = 56 x=8 y=16 so, on day1: 8 pencils and 16 notebooks day2: 16 pencils and 40 notebooks
*March 21, 2016*

**math help pls pls pls**

But yes, only C is a binomial.
*March 21, 2016*

**Algebra**

If the peanuts cost $x/kg, 5x + 3(x+0.20) = 7.80
*March 21, 2016*

**science**

light slows down when passing through the glass. Each color slows down a different amount.
*March 21, 2016*

**Algebra 2**

You are correct.
*March 21, 2016*

**Math**

you can't put a 3-D plane into a 2-D line form.
*March 21, 2016*

**Precal**

cosAcosB + sinAsinB = cos(A-B) so, what is 5π/16 - π/16?
*March 21, 2016*

**integration!!help urgently**

Hmmm. font problem, I guess. It's theta. Let's use t z = tan(t) z^2+1 = sec^2(t) dz = sec^2(t) dt
*March 21, 2016*

**integration!!help urgently**

this is a standard form. Let z = tanθ z^2+1 = sec^2θ dz = sec^2θ dθ Plug that in and see how simple it is. You can also use z = sinhθ but that's less common.
*March 21, 2016*

**Math**

42 cm/s
*March 21, 2016*

**Pre-Algebra**

42%
*March 21, 2016*

**algebra 1 math**

geez! use one name, and give it a rest! see http://www.jiskha.com/display.cgi?id=1458591353
*March 21, 2016*

**magh**

well, either #1 < #2 or #1 > #2
*March 21, 2016*

**Math**

1/5 of 23 and 4/5 of 23
*March 21, 2016*

**Algebra**

no idea what time, but the distance x will be -b/2a = -1/-.014 = 71.4 ft extra credit: given f(x) with x in feet, what is f(t), with t in seconds? recall that x(t) = v cosθ where θ is the angle of takeoff.
*March 21, 2016*

**algebra 1**

In that case, I suspect the x-y values are reversed.
*March 21, 2016*

**algebra 1**

(12-9)/(13-5) = 3/8 (16-12)/(23-13) = 2/5 (16-9)/(23-5) = 7/18 4/5 is nowhere any of those slopes. The handy calculator at http://ncalculators.com/statistics/linear-regression-calculator.htm comes up with y = .3893x + 7.0123 Looks like none of them is close, since all their ...
*March 21, 2016*

**Math**

when dividing, (a) divide coefficients (b) subtract exponents So, that will be (6/10) a^(3-5) b^(2-4) = 3/5 a^-2 b^-2 = 3/5 1/a^2 1/b^2 = 3 -------------- 5 a^2 b^2
*March 21, 2016*

**algebra 1**

see http://www.jiskha.com/display.cgi?id=1458591353
*March 21, 2016*

**Linear Algebra**

well, C^-1 is (1/2)[1,-1;-1,3] so just crank it out. You can check your answer here. Note the notation for matrices. http://www.wolframalpha.com/input/?i=inverse+{{3,1},{1,1}}
*March 21, 2016*

**Geometry**

the law of sines says that sinC/c = sinA/a sinC/83 = sin31°/44 sinC = 0.9715 So, C = 76.3° A+B+C = 180, so B = 180 - (31+76.3) = 72.7°
*March 21, 2016*

**math**

Nut A won't fit bolt A Bolts A&B are the same. so, ...
*March 21, 2016*

**math**

can't say
*March 21, 2016*

**math**

ever hear of normal + and - signs? Why the em dashes and large + signs? I assume you want to prove that (SinA-cosA)/(sinA+cosA) + (sinA+cosA)/(sinA-cosA) = -2/cos2A put it all over a common denominator and you have (sinA-cosA)^2 + (sinA+cosA)^2...
*March 21, 2016*

**math**

c'mon -- A does not fit A Bolts A&B are the same.
*March 21, 2016*

**math**

read the information. A and B are the same. C is different from the others.
*March 21, 2016*

**Maths**

you know that the domain of √u is u>=0. So, you need 1-3x >= 0 for the other, the domain is all reals except where the denominator is zero. So, where 2x-6=0, that value is excluded. D = (-∞,3)U(3,∞)
*March 21, 2016*

**math - eh?**

I assume that ^ means square root, but what do < and > mean? They clearly are not used here as comparisons (less than, greater than). and then you don't provide any choices for completion.
*March 21, 2016*

**Pre Algebra - BZZZTTT**

posting the same incomplete and contradictory information isn't going to help. Does this question relate to some previous problem whose information you have omitted?
*March 21, 2016*

**Pre Algebra**

c = 420h
*March 21, 2016*

**Pre Algebra Test**

Looks like D to me
*March 21, 2016*

**Trigonometry**

recall that the equation of motion is y = h0 + tanθ x - g/(2v^2) sec^2θ x^2 so, y = 200 + 1.11x - 0.00001787x^2 y=0 at x=62278.7 ft or 11.8 miles
*March 21, 2016*

**maths**

the magnitude is 6*7*sin120° The direction is perpendicular to both vectors. Review the definition of a cross product. The determinant form is easiest to compute if you have the x,y,z components.
*March 21, 2016*

**Math**

If she does n problems on each of the first 5 days, then that makes 5n. So, she will have 250-5n left on the 6th day.
*March 21, 2016*

**Pre Algebra**

A,C,D all say the car decelerates. But, the speed increased from 4mi/hr to 6mi/hr, so only B is a logical choice. But B's language is all messed up. How can the speed increase from 4mi/hr to 2mi/hr? And then decrease to 5 mi/hr? And there seems to be some time missing. ...
*March 21, 2016*

**Pre Algebra - incomplete**

all 4 choices describe possible movements. But you did not provide any indications of what the user was doing to control the car, or what the car was doing initially.
*March 21, 2016*

**Math Help**

in that case, you are correct.
*March 21, 2016*

**Math Help!**

of what?
*March 21, 2016*

**Algebra**

it missed green 12 times. So, P(~green) = 12/20
*March 21, 2016*

**geom**

If you have a rectangular field, a square gives the maximum area of 25^2 = 625. A regular pentagon has an area of 688. As you add more sides, a regular n-gon with more sides has greater area. Reiny's circle of radius 50/π has the maximum possible area of 2500.
*March 21, 2016*

**@collins**

not quite. You got m right, but 3 = (-1/3)(2)+c 3 = -2/3 + c 3 + 2/3 = c 11/3 = c y = -1/3 x + 11/3 why did you change 9 to -9? It didn't change sides. If you check Reiny's equation y-3 = (-1/3)(x-2) y-3 = -1/3 x + 2/3 y = -1/3 x + 11/3 You may want to work on logs and...
*March 21, 2016*

**question !!!**

You must not have looked too hard. I did a google on schaum outline algebra and got many hits, the first of which was at amazon.com http://www.amazon.com/Schaums-Outline-Elementary-Algebra-Outlines/dp/0071611630 If that's not the book you want, just change the subject of ...
*March 21, 2016*

**Linear Algebra**

(9,4) = 9*(1,0) + 4*(0,1) So, T(9,4) = 9T(1,0)+4T(0,1) = 9(3,2) + 4(-1,4) = (27,18) + (-4,16) = (23,34)
*March 21, 2016*

**computer programing**

sounds good to me. Although a file need not be part of a database. Plenty of them stand alone.
*March 21, 2016*

**MATH_2016ii**

161 = 13*12 + 5 (i) after 4 weeks he had 5 + 4*12 = 53 (ii) n/2 (5+12(n-1)) = 809 n ≈ 11.7 So, after 12 weeks he had more than 809 marbles
*March 21, 2016*

**MATH_2016**

the common ratio can be found by dividing any term by the previous one. clearly r = -1/2 So, Tn = -100 (-1/2)^(n-1) = 200/(-2)^n
*March 21, 2016*

**Algebra**

Holy smoke! Did you do all those special characters by hand?!?!? a+c = 220 5a+4c = 955 Now just solve for a and c.
*March 21, 2016*

**calculus**

v(t) = dr/dt = <5cost, 3sect tant> a(t) = dv/dt = <-5sint, 3sect(2sec^2t-1)> just do normal derivatives of trig functions
*March 21, 2016*

**math**

33 1/3% = 33.33333% = 0.33333... = 1/3 study up on common fractions and their repeating decimal representation.
*March 21, 2016*

**Physics**

F=ma, so a = 30/5 = 6 m/s^2 s = 2 + 3t^2 = 10 so, t = √(8/3) ≈ 1.633 s v = at = 6*.1633 = 9.80 m/s
*March 21, 2016*

**geometry**

the area (and hence the number of worms) will grow as the square of the linear scale factor. That is, her square will have an area 8^2 = 64 times as big.
*March 20, 2016*

**math help pls pls pls**

1st question: do you know what the standard form is? review your materials. I'm sure it explains it there.
*March 20, 2016*

**calculus**

dp/dt = 2√(pt) dp/√p = 2√t dt 2√p = 4/3 t^(3/2) + c p = (2/3 t^(3/2) + c)^2 Now plug in t=1 to find c.
*March 20, 2016*

**Math**

Nope. This is an example of poor notation. What he means is -4(2x + 5)^2 but doesn't know how to write it. You'll see this often here. So, to expand that we have -4((2x)^2 + 2*2x*5 + 5^2) = -4(4x^2+20x+25) = -16x^2 - 80x - 100
*March 20, 2016*