Sunday
December 4, 2016

# Posts by Reiny

Total # Posts: 36,897

base --- x height = x-1 area of triangle = (1/2) base x height (1/2)(x)(x+1) = 105 x^2 + x = 210 x^2 + x - 210 = 0 (x+15)(x-14) = 0 x = -15 or x = 14, but x > 0 base is 14 cm, height is 15 cm check: area = (1/2)(15)(14) = 105 all is good!
August 1, 2016

maths
after markup ---- > 140% after discount --- .75(140)% = 105% so the trader makes a profit of 5%
August 1, 2016

maths
right now: number of girls ---- x number of boys --- x+15 after increase: girls ---- 1.15x boys ---- 1.2(x+15) boys - girls = 29 1.2(x+15) - 1.15x = 29 1.2x + 18 - 1.15x = 29 .005x = 11 x = 220 there are 220 girls and 235 boys or a total of 455 students check: 1.2(235) = 282 1...
August 1, 2016

math
I do not understand the question.
August 1, 2016

Calculus
Let the right-hand corner vertex be P(x,y) but 3x+2y = 1 y = (1-3x)/2 or 1/2 - (3/2)x area = xy = x(1/2 - (3/2)x) = (1/2)x - (3/2)x^2 d(area)/dx = 1/2 - 3x = 0 for a max of area 3x = 1/2 x = 1/6 y = 1/2 - (3/2)(1/6) = 1/4 ---> P is (1/6 , 1/4) max area = xy = (1/6)(1/4) = 1...
August 1, 2016

PreCalculus
You didn't define your x and y, but I will assume that they represent length and width. So your first equation of xy = 30 is correct Your second equation makes no sense I will let x be one of the sides costing \$55/ft From the data, I get Cost = 40x + 15(x+2y) = 40x + 15x...
August 1, 2016

Math
13/9 + 10/3 + 4 = 13/9 + 30/9 + 36/9 = ...
August 1, 2016

maths
The slope of a line equals tan A, where A is the angle that the line makes with the x-axis So the slope of your line is tan (-135°) = 1 then y = x + b but (3,4) lies on it, ... 4 = 3 + b b = 1 y = x + 1 or x - y = -1
August 1, 2016

math (integral)
You probably meant y=e^(-x^2) look at the graph http://www.wolframalpha.com/input/?i=y%3De%5E(-x%5E2) the maximum ordinate is y = 1 however, the function never reaches the x-axis, so there is a "gap". Unless you left out some vertical boundaries, the question is bogus.
July 31, 2016

math (integral)
Did you mean y = ln x ? , I will assume you did Make a sketch to see the region in question. so you want ∫ lnx dx from x = 1 to e = [xlnx - x] from 1 to e = elne - e - (1ln1 - 1) = e - e - 0 + 1 = 1 (the integral of lnx should be in your repertoire of standard integrals)
July 31, 2016

Math
not enough information: Are the chairs in a line? Are the chairs in a circle? Suppose they are in a line. Number of ways to choose 5 of the 8 chairs to seat the boys = C(8,5) = 56 but for each of those choices, we can arrange the 5 boys in 5! ways. number of ways to seat 5 ...
July 31, 2016

maths
We could do it algebraically but there are so few choices, let's just take the cases. "its unit's digit exceeds twice its ten's digit by 2" ---> 14, 26, 38, 4x, the x would have to be 10 so 14, 26, or 38 in which of these do we get a product of 24 from...
July 31, 2016

algebra
x^2 + x^2/(x+1)^2 = 3 times (x+1)^2 x^2(x+1)^2 + x^2 = 3(x+1)^2 x^2(x^2 + 2x + 1) + x^2 = 3(x^2 + 2x + 1) x^4 + 2x^3 + x^2 + x^2 = 3x^2 + 6x + 3 x^4 + 2x^3 - x^2 - 6x - 3 = 0 nasty equation, so I tried Wolfram, http://www.wolframalpha.com/input/?i=x%5E4+%2B+2x%5E3+-+x%5E2+-+6x...
July 31, 2016

kaushik
Simple interest or compound interest? at simple interest, let the original be \$x change our times to months ---> 2 yrs, 3 months = 27 months interest = x(.11)(27/24) = 99x/800 x+99x/800 = 4491 x(1 + 99/800)= 4491 x = 3996.44 in 3 years: amount = 3996.44 + 3996.44(.11)(3) = ...
July 31, 2016

math
assuming log2 (4y) means log2 (4y) I could write 5 as log2 32 so we have: 5 - log2 (4y) = log2 32 - log2 (4y) = log2 (32/(4y)) = log2 (8/y)
July 30, 2016

pre algebra
let the smaller be x let the larger be 44+x translate: "Five times the smaller is equal to 8 more than the larger" ----> 5x = 44+x + 8 4x = 52 x = 52/4 = 13 smaller is 13 , larger is 57 check 57-13 = 44 , check!! 5 times the smaller is 65 is 65 greater than 57 by ...
July 30, 2016

math
one number .... x other numbr .... 2x + 3 x(2x+3) = 35 2x^2 + 3x - 35 = 0 it factors .... (2x-7)(x+5) = 0 x = 7/2 or x = -5 but since the numbers are negative x = -5 one number is -5 the other is -7
July 30, 2016

Calculus AB
From you subject title, I will assume you have studied vectors. let r be the resultant vector 40 min at 3.5 mph = 7/3 miles 20 min -----> 7/6 miles 60 min -----> 7/2 miles 15 min -----> 7/8 miles r = ((7/3)cos0, (7/3)sin0) + ((7/6)cos245, (7/6)sin245) + ((7/2)cos345...
July 30, 2016

Calculus AB
So the other angle must be 180-2(55) or 70° draw in the height, h You now have a right-angled triangle, let the hypotenuse be x you can find the height by tan 55° = h/10 you can find the side by cos 55° = 10/x once you have x, you can find the perimeter. once you ...
July 30, 2016

Calculus AB
July 30, 2016

Calculus AB
If you make a good sketch , this is not that hard I labeled the cars as A for the farther none, and B as the closer one. Let C be the base of the building So we want to find AB Two right-angled triangles, were clearly the angle at A is 29.5° and the angle at B is 38.2°...
July 30, 2016

Calculus AB
Let's visualize what we have here: recall that cos Ø = adjacent/hypotenuse and arccos((x+1)/2) mean we have an angle Ø so that cos Ø = (x+1)/2 so construct a right-angled triangle with base of x+1 and hypotenuse 2 and base angle of Ø Let the ...
July 30, 2016

Math
4*15-11+8-2 = 55
July 30, 2016

Maths
just plug in n = 1, n = 3, n = 5 If will do the n = 3 S(n) = 3(3) - 2 = 7
July 30, 2016

Math
Probably meant to type: x= 2-3t, y= -1+5t from x= 2-3t, -----> t = (2-x)/3 rom y= -1+5t ---> t = (y+1)/5 (2-x)/3 = (y+1)/5 3y+3 = 10 - 5x 5x + 3y = 7 slope = -5/3
July 30, 2016

Math
What is a "po" ?? are we solving 4(4x)^2 + 2(4x) + 5 = 0 ?? (we "solve" equations, you had no equation) let 4x = y, so your equation becomes 4y^2 + 2y + 5 = 0 y = (-2 ± √-76)/8 = (-2 ± 2√19 i)/8 = (-1 ± √19 i)/4 4x...
July 29, 2016

MATH
the way you typed it ... a = -(1)^n 1^anything = 1 so a = -1
July 29, 2016

math
a=2/3b 3a = 2b b = 3a/2 c=3/2b 2c = 3b b = 2c/3 thus: 2c/3 = 3a/2 4c = 9a 4/9 = a/c a : c = 4 : 9 notice 2/3b ≠ 2/(3b) I assumed you meant it the way you typed it.
July 29, 2016

statistics
it said "without replacement" , so the prob that the second is faulty is not 15% Bernie, what part of my solution did you not like ? http://www.jiskha.com/display.cgi?id=1469831346
July 29, 2016

math
There are actually more than what I gave you. Mine are only from the addition of these angles. How about subtractions ? e.g. 45 - 30 = 15 Can you find some more?
July 29, 2016

math
How would you get 145°
July 29, 2016

math
mmmh??? I could do a 30°, 45°, 60° , 90° , 75°, 105°, 120°, 135°, 150°, 165° Can you see any I missed ?
July 29, 2016

Maths
My assumption is that this question contains a typo. The effect is that I can't do the question.
July 29, 2016

math
complementary angles add up to 90° let the two angles be 3x and 2x, then their difference is x but 3x + 2x = 90 5x = 90 x = 18 the difference in the two angles is 18° check: one is 3(18) = 54 the other is 2(18) = 36 and what is their difference ??
July 29, 2016

Math
width ---- w length ---- w+5 P = 2w + 2(w+5) = 2w + 2w + 10 = 4w + 10 4w + 10 ≤ 150 4w ≤ 140 w ≤ 35 max width is 35 m
July 29, 2016

Math
I am a bit confused myself, unless you have a typo. I will assume you meant your first set to be x = 3-2t, y = -2 + 5t so -1+ 3s = 3 - 2t ---> 2t + 3s = 4 ** and -2 + 5t = 5 - 9s ---> 5t + 9s = 7 *** 3 times ** ---> 6t + 9s = 12 subtract *** t = 5 back in ** 10 + 3s...
July 29, 2016

statistics
done, look back
July 29, 2016

statistics
prob = (3/20)(2/19) = 3/190 same question as: I have 20 marbles of which 3 are red I choose 2 without replacement, what is the probability that they are both red
July 29, 2016

math
So we need a triangle with area of 30 cm^2 let the length of each of the equal sides of the isosceles triangle be x, and the height be h h^2 + 6^2 = x^2 ** but we also know that the area of the triangle is (1/2)(12)h = 30 6h = 30 h = 5 then in ** 25 + 36 = x^2 x^2 = 61 x = &#...
July 29, 2016

math
By the definition of a rhombus , all sides are equal, so if one side is 10, then all sides are equal to 10. Also, the diagonals bisect each other at right angles creating 4 congruent right-angled triangles. Looking at one of these triangles, we have sides 3x, 4x, and ...
July 29, 2016

oops - Calculus
dont' know where the 65 came from simply change it to 64 and complete the solution, you should get 48 and 16
July 28, 2016

Calculus
A product is the result of a multiplication. "product of one of them plus the cube of the other" is mathematically confusing, since "plus" implies addition. I will assume you meant: "product of one of them with the cube of the other" let the one ...
July 28, 2016

maths
(3-√-16) = 3 - 2i recall: √-1 = i √-16 = √4 x √-1 = 2i
July 27, 2016

Math
let the two numbers be x and x+1 x + x+1 = S 2x = S - 1 x = (S-1)/2 The square of the larger number minus the square of the smaller number = (x+1)^2 - x^2 = x^2 + 2x + 1 - x^2 = 2x + 1 = (S-1) + 1 = S check: let's take 37, and 38 sum = 75 square of larger =1444 square of ...
July 27, 2016

Math
15/4 = 3.75 or = 3 3/4 as a mixed fraction or how about (1/2)(7.5) or (1/4)(15 or .....
July 27, 2016

GP
so the GP terms are: a+d, a+3d, and a+6d (a+3d)/(a+d) = (a+6d)/(a+3d) (a+6d)(a+d) = (a+3d)^2 a^2 + 7ad + 6d^2 = a^2 + 6ad + 9d^2 ad = 3d^2 divide by d a = 3d common ratio : r = (a+3d)/(a+d) = 6d/(4d) = 3/2
July 27, 2016

Maths
Did you look at http://www.jiskha.com/display.cgi?id=1469612090
July 27, 2016

Maths
after 1 day, the two clocks will show a difference of 5 minutes after 2 days, the two clocks will show a difference of 10 minutes ... after n days the clocks will show a difference of 5n minutes. One day consists of 1440 minutes. number of days needed to make up this time = ...
July 27, 2016

maths
Since you gave the dimension of only one wall, let's assume that the room is square. As Steve showed in his calculation, one wall has an area of 5x3 or 15 m^2 So 4 walls have an area of 60 m^2 if 6 litres cover 10 m^2 1 L will cover 10/6 or 5/3 m^2 number of litres of ...
July 27, 2016

Algebra
time of Bell's sprinklers --- x hrs time of Patterson's ------- 65-x hrs solve for x: 15x + 25(65-x) = 1225
July 26, 2016

geometry
well, it could either be 8, 8, 10 or 8, 10, 10 so which fits?
July 26, 2016

MAth Trig
72° = (π/180)(72) radians = 2π/5 radians arc = rØ 32 = 2π/5 r r = 80/π so the diameter is 160/π cm or appr 50.9 cm or 72/360 = 32/(2πr) 144πx = 32(360) x = 80/π , as above
July 26, 2016

Maths
The two scales where they coincide are -40 degrees in both units There are many places in the world where such temperatures exist. In my Canada these are the top 10 lowest temperatures recorded. http://www.durhamregion.com/whatson-story/5153897-top-10-coldest-temperatures-...
July 26, 2016

Math
Abegail --- x years Alger ---- x-7 years x(x-7) = 144 x^2 - 7x - 144 = 0 (x - 16)(x + 9) = 0 x = 16 or x = -9, the last does not make sense. sub back in my definitions
July 26, 2016

Army school math
let each of the equal sides be x 2x + 6 = 26 x = 10 make a sketch of the triangle, draw in its height h h^2 + 3^2 = 10^2 h = √91 area = (1/2)(6)√91 = 3√91 cm^2 which is the same as DrBob's answer
July 26, 2016

Trigo
I made a sketch, showing two right-angled triangles. One is : base angle 28°, height = 30 tan28 = 30/base base = 30/tan28 other triangle: let the distance between ships be x tan23° = 30/(base + x) base + x = 30/tan23 x = 30/tan23 - base = 30/tan23 - 30/tan28 = 14.25 m
July 26, 2016

physics
first leg: a = 1 v = t + c when t = 0 , v = 0 , thus c = 0 v = t s = (1/2)t^2 so after 20 seconds, s = (1/2)(400) = 200 m v = 20 m/s (or 72 km/h ) second leg: at constant speed, no acceleration v = 20 m/s s = rate x time = 20(1800) = 36000 m last leg: a = ? v = at + 20 when t...
July 26, 2016

Math
size of side of square to be cut out --- x cm volume = (25-2x)(32-2x)(x) = 1575 expanding we get: 4x^3-114x^2 + 800x = 1575 4x^3 - 114x^2 + 800x - 1575 = 0 messy to solve, gave up trying to factor, and used Wolfram: http://www.wolframalpha.com/input/?i=solve+4x%5E3+-+114x%5E2...
July 25, 2016

CHECK MY ALGEBRA 2
Scott was right, the denominator causing the vertical asymptote at x = -2 is x+2 final answer: f(x) = (x-4)/( (x-4)(x+2) )
July 25, 2016

pre cal
You should know that we can only take logs of positive numbers, so x-1 > 0 x > 1 so the vertical asymptote is x = 1
July 25, 2016

Math
the the circle be x^2 + y^2 = r^2 then y = √(r^2 - x^2) or (r^2 - x^2)^(1/2) let the length of the rectangle be 2x, and the height be 2y then the vertex in quadrant I is (x, (r^2 - x^2)^(1/2) ) area = 2x(2y) = 4xy = 4x((r^2 - x^2)^(1/2)), remember r is a constant d(area...
July 25, 2016

let x = π/6 for easier typying so your 1/cos2 * π/16 - 1/cot2 * π/16 = 1/cos^2 x - 1/cot^2 x = sec^2 x - tan^2 x since sec^2 x = 1 + tan^2 x , = 1 + tan^2 x - tan^2 x = 1
July 25, 2016

pre cal
plug in your values, assuming you meant f(x) =a (2)^(bx) and not what you typed. for (0,3) , 3 = a(2)^0 --> 3 = a for (1,4) , 4 = 3(2)^b 2^b = 4/3 take logs of both sides, and use log rules b log2 = log4 - log3 b = (log4 - log3)/log2 = appr .415037
July 25, 2016

math
smaller number --- x larger number ---- x+5 "the sum of two numbers is 25" translate into an equation and solve.
July 23, 2016

Maths
Use your definitions: a + ar^2 = 7/3 a( 1 + r^2) = 7/3 ** ar + ar^3 = 7/4 a(r + r^3) = 7/4 *** divide *** by ** (r + r^3)/(1 + r^2) = (7/4) / (7/3) = 3/4 4r + 4r^3 = 3 + 3r^2 4r^3 - 3r^2 + 4r - 3 = 0 r^2(4r - 3) + 1(4r-3) = 0 (4r-3)(r^2 + 1) = 0 4r = 3 or r^2 = -1 , the last ...
July 23, 2016

Math - Trig
All you have to do is follow the same steps I used to get the answer of 4.51 http://www.jiskha.com/display.cgi?id=1469238292
July 22, 2016

Math
Stacey/ba, please don't switch names 7.8 + sin3.5 (pi/6(t-3)) = 10.29 sin3.5 (pi/6(t-3)) = 2.49 not possible, sin(?) cannot be > 1 when you first posted this, you had 3.5sin (pi/6(t-3)) I will change it to 7.8 + 3.5sin (pi/6(t-3)) = 10.29 3.5sin (pi/6(t-3)) = 2.49 sin (...
July 22, 2016

correction - Math
forget the first part of my solution, I read it as 3x^3−x^2+bx−24 we know : f(x) = ax^3−x^2+bx−24 since x-2 is a factor, f(2) = 0 f(2) = 8a - 4 + 2b - 24 = 0 8a + 2b = 28 4a + b = 14 ** f(-4) = 0 -64a - 16 - 4b - 24 = 0 -64a - 4b = 40 16a+ b = -10 *** ...
July 22, 2016

Math
ax^3−x^2+bx−24 = (x-2)(x+4)(ax + c) the ax^3 can only come from the multiplication of the first terms of each of the binomials, (x)(x)(ax) = 3x^3 ----> a = 3 the -24 can only come from the multiplication of the last terms of each of the binomials, (-2)(4)(c) = -...
July 22, 2016

Futher maths
tanØ + 2secØ = 2cotØ + 3cscØ sinØ/cosØ + 2/cosØ = 2cosØ/sinØ + 3/sinØ multiply each term by sinØcosØ sin^2 Ø + 2sinØ = 2cos^2 Ø + 3cosØ sinØ(sinØ + 2...
July 22, 2016

math
John's rate = 1/4 Michael's rate = 1/x combined rate = 1/4 + 1/x = (x+4)/(4x) given: 1/( (x+4)/(4x) ) = 3 4x/(x+4) = 3 4x = 3x + 12 x = 12 Michael alone would take 12 hours check: combined rate = 1/4 + 1/12 = 1/3 time at combined rate = 1/(1/3) = 3
July 21, 2016

math
Think about the method and the pattern if you had 80% ----> 80/100 = 4/5 if you had 8% -----> 8/100 = 2/25 if you had .8% ----> .8/100 = 8/1000 = 1/125 your .8/100 * 10/10 = 8/1000 , not 8/100
July 21, 2016

Math
"Which statement best describes the sum 7/8? " - first of all 7/8 is not the "sum" - secondly, there is no mathematical reason for Jack to come up with 7/8 - thirdly , this is a silly question.
July 21, 2016

Math
" ...all the possible values for angle Ø, given that Ø =-3/8and 0<theta<3pi " this makes no sense, did you skip the trig function in front of Ø, such as sinØ = -3/8 ??
July 21, 2016

Math
one question at a time. period of your cosine is 4 s so 2π/k = 4 4k = 2π k = π/2 so let's start with A = cos (πt/2) the min is .08, and the max is .82, thus a = (.82-.08)/2 = .37 so far: A = .37 cos (πt/2) the min of that is .37, but we want the ...
July 21, 2016

Math
Are you assuming the relation follows a trig function, either a sine or cosine ?
July 21, 2016

Math
area to be covered = 4(90) or 360 square feet, assuming your room is square. number of gallons = 360/120 = 3 gallons
July 21, 2016

Arithmetic/Geometric Sequence
A quick check shows it is neither arithmetic nor geometric, so mess around with it a bit how about (1/18)( 12, 6, 4, 3, ....) , 18 is the LCD notice : 12/1 = 12 12/2 = 6 12/3 = 4 12/4 = 3 so it looks like term(n) = (1/18)(12/n) = 2/(3n)
July 21, 2016

Math
Chandra ---- x years Ben's age ---- x+6 yrs Ali's age ---- x+6 + 3 = x+9 yrs (x + x+6 + x+9)/3 = 10 solve for x, then back-sustitute.
July 21, 2016

Calc
P = 5cos (pie/2 (t)) +5 the period of this function is 2π/(π/2) = 4 for the lowest productivity, we need the minimum of the function. we know that cos (pie/2 (t)) has a minimum of -1 then 5cos (pie/2 (t))has a minimum of -5 and 5cos (pie/2 (t)) +5 has a minimum of 0 ...
July 20, 2016

math
cotx = 6/5 ---> tanx = 5/6 secy = 3/2 ---> cosy = 2/3 sketch your triangles in quad I using Pythagoras, if tanx = 5/6 r^2 = 25 + 36 = 61 r = √61 if cosy = 2/3 by Pythagoras: 2^2 + Y^2 = 3^2 Y = √5 tany = √5/3 tan(x+y) = (tanx + tany)/(1 - tanxtany) = (5...
July 20, 2016

Math - Trig
the period of your function is 2π/(π/6) or 12. So it represents 1 year of temperature change. first look at the graph: http://www.wolframalpha.com/input/?i=plot+y++%3D+12.5+%2B+15.8sin+(%CF%80%2F6+x+%E2%88%922%CF%80%2F3)+,+y+%3D+12.5+from+0+to+12 notice the sine ...
July 20, 2016

Math - Trig
period = 2π/k in our case k = 2π/3 period = 2π/(2π/3) = 3 so one rotation takes 3 seconds, thus 4 rotations would take 12 seconds The radius of the wheel would be the amplitude of your cosine curve which is 17.5 cm Here is a graph of your courve: http://www...
July 20, 2016

Math
So the zero can only come from the numerator, thus r^2 + 5r + 6 = 0 (r+2)(r+3) = 0 r = -2 or r = -3 BUT, as noted in your other replies, r cannot be -2 so r = -3 which is C
July 20, 2016

Math
let's graph the original function http://www.wolframalpha.com/input/?i=plot+y++%3D+%E2%88%92+sin+(3x+%2B+%CF%80%2F3+)+%E2%88%92+2 Notice that the curve does not cross or touch the x-axis, that is , it can never be zero. Therefore the reciprocal can never be undefined and ...
July 20, 2016

Math
We all know that 4 quarters make up 1 dollar. so how many quarters do we need to make up \$50.50 ?
July 20, 2016

math
let the three numbers be x-1, x, and x+1 , where x is the middle number x-1 + x + x+1 = 18 3x=18 x=6 so the middle number is 6, and the three numbers are 5,6, and 7 btw, You could define the numbers any way you want. I could say, let the first number be (5x+7), then the next ...
July 20, 2016

Math
1/4 -1/x+6= 1/x ? I have this feeling you meant 1/4 - 1/(x+6) = 1/x multiply by 4x(x+6) , the LCD x(x+6) - 4x = 4(x+6) x^2 + 6x - 4x = 4x + 24 x^2 - 2x - 24 = 0 (x-6)(x+4) = 0 x = 6 or x = -4
July 20, 2016

maths
total trip = 2(27) + (11/2)(20) km = 164 km total time = 2+11/2 or 7.5 hours average speed = 164/7.5 or appr 21.87 km/h
July 20, 2016

trigonometry
2sin(t)cos(t)-cos(t)+2sin(t)-1=0 cost(2sint - 1) + (2sint - 1) = 0 (2sint - 1)(cost + 1) = 0 sint = 1/2 or cost = -1 if sint = 1/2 t = π/6 or t = 5π/6 if cost = -1, look at your cosine curve, t = π
July 19, 2016

Math
make a sketch of the first few bounces and you will see: 1 bounce --- 56 m 2nd bounce = 2(28) = 56 3rd bounce = 2(14) = 28 4th bounc = 2(7) = 14 5th bounce = 2(3.5) = 7 6th bounce = 2(1.75) = 3.5 add them up to get ..... 164.5 or: from the 2nd on , we have a geometric sequence...
July 19, 2016

mathes
The room is 800 cm by 600 cm, and the tile is 8 cm by 10 cm, so the tiles will fit exactly along either side. (ignoring any grouting gaps) area of floor = 480,000 cm^2 area of one tile = 80 cm^2 number of tiles = 480,000/80 or 6000 tiles or tiles along the length = 800/8 = 100...
July 19, 2016

math
cosine law: x^2 = 2.4^2 + 2.4^2 - 2(2.4)(2.4)cos 30° ....
July 19, 2016

Math
This one is a bit different. In the first one, the "16" was the value of one of the terms of the ratio. In this one, the "240" is the sum of the terms of the ratio. Let Anton's number of stamps be 4x let Maria's number be 2x 4x + 2x = 240 x = 40 ...
July 19, 2016

Find the probability
following your "steps" prob(both red) = C(4,2)/C(9,2) = 6/36 = 1/6 or , straightforward way .... prob = (4/9)(3/8) = 1/6
July 19, 2016

Calculus
let y = 1/sinx = (sinx)^-1 dy/dx = -1(sinx)^-2 (cosx) = cosx (1/sin^2 x) = cosx/sinx * 1/sinx = cotx cscx
July 18, 2016

Calculus the derivative
Did you not look at my solution to the same question ? http://www.jiskha.com/display.cgi?id=1468890453 All I can see wrong with it, I labeled part D as B for B all you have to do it sub t = 1 and t = 3 into your velocity equation: v = -32t.
July 18, 2016

Calculus the derivative
A . correct B. for the average velocity no Calculus is needed P(1) = -16(1) + 1454 = 1438 P(3) = -16(9) + 1454 = 1310 average velocity = (1310 - 1438)/(3-1) = -64 ft/s C. now you want to set -32t = -64 t = 2 E. correct F. I disagree. you want P(t) = 0 -16t^2 + 1454 = 0 t^2 = ...
July 18, 2016

Math
i = .0275/12 = .002291666... what is 5700(1.00229166..)^144 ?
July 18, 2016

MATH
just use your definitions: the terms would be a, ar, and ar^2 so a(ar)(ar^2) = 343 a^3 r^3 = 343 (ar)^3 = 343 ar = 7 or a = 7/r a + ar + ar^2 = 49/2 a(1 + r + r^2) = 49/2 (7/r)(1 + r + r^2) = 49/2 7/r + 7 + 7r = 49/2 times 2r 14 + 14r + 14r^2 = 49r 14r^2 - 35r + 14 = 0 2r^2 - ...
July 18, 2016