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March 26, 2017

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Posts by Reiny

Total # Posts: 38,076

Math
surface area = base + 4 sides = 40(25) + 2(40)(6) + 2(25)(6) m^2 = ..... Once you have the total surface area, multiply that by your cost of 135 per square metre.
February 1, 2017

Math
So basically all we need is the area of the triangle plus the area of the circle. area = (1/2)(10)(8) + ?(4)^2 = 40 + 16? = ...... you do the arithmetic
February 1, 2017

Maths
first of the numbers ---- x the next odd number ---- x+2 x(x+2) = 195 x^2 + 2x - 195 = 0 (x+15)(x-13) = 0 carry on
February 1, 2017

Algebra
Assuming that your "new math" follows the traditional order of operation, just do it. a ? b = 2a ? 3b then: (1 ? 2) ? 7 = (2 - 6) ? 7 = -4 ? 7 = -8 - 21 = -29
February 1, 2017

Maths
let the sides be 3x, 4x, and 5x solve for x and sub into my definitions 3x+4x+5x = 12 you should be able to do it in your head. Did you notice that your triangle is also right-angled?
February 1, 2017

Math
Just make the changes to my solution I gave you before you found the typo http://www.jiskha.com/display.cgi?id=1485954263
February 1, 2017

Maths
length of base = 50-10 = 40 cm width of box = 40-10 = 30 cm height of box = 5 cm volume = length x width x height = ...... cm^3
February 1, 2017

Kevin ? - Math
The first part I already answered in your previous post. If the gradiant is 34, the diameter is quite steep. Lets find its equation: y = 34x + b but (1,2) lies on it, so 2 = 34(1) + b b = -32 y = 34b - 32 the equation of the circle I described in the earlier post is (x-1)^2...
February 1, 2017

math
nope .... amount = 500 (1.25)^m , where is the number of minutes (an increase of 25% results in what you started with plus the increase or 1 + .25 = 1.25 e.g. suppose an article costs $100 a 25% increase would be $25 so the cost is $125 that is: 100(1.25) = 125 )
February 1, 2017

Math
The line AB would be the horizontal diameter of a circle with centre (1,2) and radius 5 So just go 5 units to the left and to the right of (1,2) A could be (-4,2) and B could be (6,2) or B(-4,2) and A(6,2) notice AB = ?(6+4)^2 + 0^2) = 10
February 1, 2017

Math
what is (26.5+31)/2 ?
February 1, 2017

Math
Follow the same steps I just showed you here http://www.jiskha.com/display.cgi?id=1485922261
January 31, 2017

Math
Follow the same steps as I just showed you when you were Bobby
January 31, 2017

Math
f'(x) = lim (f(x+h)?f(x))/h , as h ---> 0 =lim (4hx?1h+5h^2)/h , as h ---> 0 = Lim (4x - 1 + 5h) , as h ---> 0 = 4x - 1
January 31, 2017

Math
4 inches ---> 6 ft 1 inch -----> 6/4 ft or 1.5 ft
January 31, 2017

maths
"4th term is 7" ---> a+3d = 7 "7th term is 13" ---> a+6d = 13 subtract them: 3d = 6 d = 2 sub back into my first equation to find a, then use the Sum of Terms formula to find sum(20)
January 31, 2017

math
The previous one is (2n-2) the next one after 2n is (2n+2
January 31, 2017

Math
8 bananas at 50 g each is 400 g what is 400/1000 times $6.50 ?
January 31, 2017

Math
x- 4/5 = 12/15 x = 4/5 + 12/15 x = 12/15 + 12/15 = 24/15 = 8/5
January 31, 2017

Math
(x-3)^2 + sin(x-3) + 7
January 31, 2017

sequence help plz
clearly an arithmetic series with a = 5 and d = 6 sum(2n) = (2n/2)(10 + (2n-1)(6)) = n(10 + 12n - 6) = 4n + 12n^2
January 31, 2017

math
so your chord is also 3 cm from the centre. construct the right-angles triangle look at the angle it makes at the centre, cosØ = 3/6 = 1/2 Ø = 60° the chord subtends an angle of 120°
January 31, 2017

MATH @Damon @ms. Sue
notice for Option 1: 1100 1210 1331 1210 / 1100 = 1331 / 1210 = 1.1 so we have a geometric progression, making the function exponentinal term(n) = 1100 (1.1)^(n-1) , where n is the number of years in Option 2: 1100 1200 1300 we have 1200 - 1100 = 1300 - 1200 = 100 we have a ...
January 31, 2017

maths
16 2/3% = 50/300 = 1/6 check: on my calculator 1/6 = .166666... or 16 2/3%
January 31, 2017

Math
500 (2^(t/12)) = 800 , where t is in hours 2^(t/12) = 1.6 take logs of both sides, and use the rules of logs t/12 log2 = log 1.6 t/12 = log 1.6/log 2 t = 12(log 1.6/log 2) = appr 8.1 hours
January 31, 2017

Algebra
John1 meant to say 3(-3x) = -9x , not -6x then 2x - 9x = 6 -7x = 6 x = -6/7 ---> not found in any of the answers, so I suspect a typo somewhere y = -3(-6/7) = 18/7 (-6/6 , 18/7) is the correct solution This answer works in both equations
January 31, 2017

Algebra
rate last year = 1300/1250 = 1.04 if rate is the same, next year: 1300(1.04) = 1352
January 29, 2017

Math
what is 8 ÷ (2/3) ?
January 29, 2017

Math
In the second term, I counted 6 of "(" and 7 of ")", so mismatched brackets. I will assume you meant: cos(x)/(1-tan(x)) + (sin (x))* cos(x))/ (sin (x)- cos(x)) then: = cosx/( 1 - sinx/cosx) + sinx cosx/(sinx - cosx) = cosx/( (cosx - sinx)/cosx) - sinxcosx/(...
January 29, 2017

Math
I usually change everything to sines and cosines (tan(x) +cot(x))/ (tan(x)*cot(x)) = (sinx/cosx + cosx/sinx) / (sinx/cosx * cosx/sinx) = (sin^2 x + cos^2 x)/(sinxcosx) / 1 = 1/(sinxcosx) ----> I know 2sinxcosx = sin 2x so sinxcosx = (1/2)sin2x = 2/sin 2x or 2 csc 2x or from...
January 29, 2017

Math
(1+tan(x))* (1+cot(-x)) = (1 + sinx/cosx)(1 + cosx/sinx) = [ (cosx + sinx)/cosx][ (sinx + cosx)/sinx] = (sin^2 x + cos^2 x + 2sinxcosx) / (sinxcosx) = (1 + 2sinxcosx)/(sinxcos) = 1/(sinxcosx) + 2 or = secs cscx + 2
January 29, 2017

math
solve these equations: 1. 20-x = 10 2. 10x - 12 = 18 at the end you say "what is the number 7" ?????
January 29, 2017

Math
greater --- x lesser --- x-1 x+x-1 = 15 solve and sub into my definitions
January 29, 2017

Geometry
clearly the ellipse has a vertical major axis centre is (2,1) , b = 3 For this ellipse: e = c/b 1/3 = c/3 c = 1 a^2 + c^2 = b^2 a^1 + 1 = 9 a^2 = 8 (x-2)^2/8 + (y-1)^2/9 = 1
January 29, 2017

Geometry
"Angle D is nine less than twice the measure of Angle C" D = 2C - 9 and we know C+D = 180 , so .....
January 29, 2017

Coordinates
Show that two of the three line segments have slopes that are negative reciprocals of each other.
January 29, 2017

Math
c(x) = 8 + 1.5x
January 29, 2017

Maths
a = 120000 m/s^2 v = 120000t + c when t=0, v = 0 , so c = 0 s = 60000t^2 + k , where s is the distance, k a constant when t=0, the plane hasn't gone anywhere so 0 = 0 + k, k = 0 s = 60000(t^2) when t = 4, s = 60000(4) = ...
January 29, 2017

Maths
draw a perpendicular from the centre to the chord. draw the radius to the end of the chord. You have a right-angled triangle with one leg of 6 and a hypotenuse of 10. Use Pythagoras
January 29, 2017

Math
That is some wind!!! I think you have a typo and meant that the plane's speed is 650 mph. however, taking it as is: let the plane's speed be x mph from city x to city y: distance = 8(x-650) from city y to city x: distance = 5(x+650) 8(x-650) = 5(x+650) solve for x , ...
January 29, 2017

Mathematics
draw the science circle totally within the math circle enter 56 in the science circle, put 17 in the science only circle 82-73 or 9 take neither science nor math.
January 29, 2017

Maths
x(1.8)(r) = x 1.8r = 1 r = 1/1.8 = .555.. so the discount rate should be .444... or appr 44.4% e.g. suppose the item cost $100 after markup, selling price = 180 to end up with $100, we have to discount it $80 80/180 = .44444 notice 1 - .4444... = .555...
January 29, 2017

Geometry
This makes no sense to me. If the octagon is equiangular (all angles are equal) , how can the side be of different lengths ?
January 28, 2017

math
Join the centres and you will have an equilateral triangle with sides 1 m Also the band will form 3 arcs , each of 120°. So the band covers the entire distance around the circle, that is, its circumference. Notice that if you complete the rectangle, we know the long side ...
January 28, 2017

math
let the time be t minutes distance covered by Ali = 48t distance covered by Tina = 62t 48t + 62t = 1320 solve for t
January 28, 2017

statistics
cutting through the chase .... prob(your stated event) = C(10,7)(1/5)^7 (4/5)^3 = 120(1/78125)(64/125) = appr .0008
January 28, 2017

Maths
from the second: 4x + 10y = 50 4x = 50-10y into the first: 50-10y - 3y = 11 -13y = -39 y = 3 then 4x = 50 - 30 x = 5
January 28, 2017

Math
sheets left after 1st week = 4/5 of 500 = 400 after 2 more weeks 3/5 of those are left = 240 or, long way: papers used in 1st week = (1/5)(500) = 100 left: 400 he uses 2/5 of those: (2/5)(400) = 160 leaving him 400 - 160 or 240 at the end of 3rd week
January 28, 2017

Algebra
|4-6|^3 - |5-9| / |3(6-5)| + |35-7)| = 8 - 4/3 + 28 = 104/3
January 28, 2017

math
The order of these items does not matter so I will use combinations Size -- C(3,1) = 3 meats --C(7,1) = 7 veggies --C(5,2) = 10 cheese -- C(4,1) = 4 number of pizzas = 3x7x10x4 = 840
January 28, 2017

Math
number of erasers ---- x number of pencils ----- x+10 22x + 14(x+10) = 446 solve for x
January 28, 2017

maths
1. Show that two of the three line segments have slopes that are negative reciprocals of each other. 2. let the fourth point be (x,y) Make a sketch to see which lines would be parallel. You will have 2 equations in 2 unknowns
January 28, 2017

math
Let the 3 numbers in GP be a , ar, and ar^2 after first change: a , ar+2, ar^2 are now in AP that is, ar+2 - a = ar^2 - (ar+2) ar^2 - 2ar + a -4 = 0 ** after 2nd change: a, ar+2 , ar^2 + 9 , are now in GP again, (ar+2)/a = (ar^2 + 9)/(ar+2) (ar+2)^2 = a(ar^2 + 9) a^2 r^2 + 4ar...
January 28, 2017

Geometry and shape
Thanks Steve, e.g. a regular hexagon or octogon , etc
January 28, 2017

Geometry and shape
Only the rhombus, equilateral means equal, a parallelogram does not necessarily have 4 equal sides
January 28, 2017

Math
No idea what you are saying.
January 28, 2017

math
First of all your third angle is 68° , not 132° You are not asked to state the lengths of the sides, simply list them in order of size. The property to use is: In any triangle , the longest side is opposite the largest angle, the smallest side is opposite the smallest ...
January 28, 2017

math
Sketch is the big thing!! On mine , I extended AC to M so that angle BMC = 60° Also you can see that angle MCB = 60° (external angle) So triangle CBM is equilater, and since CM = 12 CB = MB = 12 Also, since ABC is isosceles and CA = CB CA = 12 now by the sine law: AB/...
January 28, 2017

maths
Use you sum(n) terms formula (11/2)(2a + 10d) = 891 but d = 15 (11/2)(2a + 150) = 891 11(2a + 150) = 1782 2a + 150 = 162 continue once you have a, just use your formula term(28) = a + 27d = .... etc
January 28, 2017

pre-algerabra
But you didn't double. but, yes, if the drawing is to scale, then you must multiply each dimension by the same scale factor for yours: 10/12.5 = 4/x 10x = 50 x = 5 so a room 10 ft by 12.5 ft ----> 4 units by 5 units in your drawing.
January 27, 2017

calculus
you should know that using the metric system, a = -4.9 m/s^2 distance = -4.9t^2 + 48t + c, where c is the initial height velocity = -9.8t + 48 given: v = -50 -50 = -9.8t + 48 9.8t = 98 t = 10 When t=0 , distance = 0+0+c = c when t = 10, distance = -4.9(100) + 48(10) + c = c - ...
January 27, 2017

Math
let the other angles be 7x and 10x so : 7x + 10x + 95 = 180 solve for x, and sub into my definitions
January 27, 2017

Math
Just did this for you in your earlier post http://www.jiskha.com/display.cgi?id=1485495789
January 27, 2017

Mathematics
original amount in A ---- x original amount in C ---- x-20 after the pouring: A has x-15-10 B doesn't matter C has x-20 + 10 = x - 10 difference between C and A = x-10 - (x-20) = x-10 -x + 20 = 10
January 27, 2017

Math (Advanced probability)
expected wins: .15(1) = .15 .05(5) = .25 .01(50) = .50 1/10000(500) = .05 total expected wins on one ticket = .95 That is, if they charged 95 cents for a ticket , everybody would break even in the long run. So to make a 40% profit, they should charge .95(1.4) or $ 1.33
January 27, 2017

Math
Looks like a binomial distribution question. I read your question to say that exactly 5 are to respond. prob(response) = .15 prob(no response) = .85 prob(5 of 15 respond) = C(15,5) (.15)^5 (.85)^10 = appr .0449
January 26, 2017

Math
You are missing the fact that they could be ordered according to increasing or according to decreasing age. Each would be ordered by age. so prob = 2/120 = 1/60 = appr .0167
January 26, 2017

Math
What is 5! ?
January 26, 2017

Math
your post is incomplete. You did not state the rate of exchange, without it any of the answers are possible
January 26, 2017

Math
The y-intercepts are of great help. It also helps to have an idea what the general shape of different polynomials are. e.g. A fourth degree generally has the shape of a W , etc Also a reasonable number of ordered pairs can be calculate and plotted to show the shape of the ...
January 26, 2017

Math
plan 1: cost = 14 + .06n , where n is the number of minutes plan 2: cost = 22 solve: 14 + .06n= 22
January 26, 2017

Pre Cal 12
Square to be cut out : x cm by x cm then the height of the box is x, and the base is 12-2x by 8-2x, where 0 < x < 4 volume = x(12-2x)(8-2x) = 36 x(6-x)(4-x) = 9 x(24 - 10x + x^2) = 9 x^3 - 10x^2 + 24x - 9 = 0 I tried x = ±1, ±3 and x = 3 was a solution. by ...
January 26, 2017

Algreba
easiest way: since your new line is perpendicular to x+2y = -7 this new line must look like 2x - y = c but (2,3) lies on it, so 2(2) -3 = c = 1 new line: 2x - y = 1
January 26, 2017

Algebra
Their normals are <3,-2,0> and <1,2,4> The only way that the two planes could not intersect is if they are parallel or plane equation is a multiple of the other. Since their normals are not parallel, neither are the planes
January 26, 2017

mathematics
for the AS" first term --- a third term -- a+2d ninth term -- a+8d but those terms form a GP (a+2d)/a = (a+8d)/(a+2d) (a+2d)^2 = a(a+8d) a^2 + 4ad + 4d^2 = a^2 + 8ad 4d^2 - 4ad = 0 d^2 - ad = 9 d(d-a) = 0 d = 0 ---> not too interesting or a = d but term 7 of the AS = ...
January 26, 2017

math
Since these are special positions, the order counts, so what is 15x14x13 ?
January 26, 2017

HELLO CAN ANYONE HELP ????!!!!!!!
I think you have a typo and you wanted to compare y = 2^x with y = log2 x They are inverses of each other. Proof: start with y = 2^x the inverse is formed by interchanging the x and y's ----> x = 2^y which in log form would be : y = y = log2 x
January 26, 2017

I'm stuck on math plz help!!
see your other post above when you posted as "R"
January 26, 2017

Statistics
The first friend will have the birthday on some given day, doesn't matter when. The prob that the second friend will have a different birthday = 364/365 the prob that the third friend will have a birthday from the other two = 363/365 prob that all three have different ...
January 26, 2017

Pre-Cal
SW is a direction. Make a sketch on the N-S-E-W grid SW is in the third quadrant, dividing it into two parts of 45° each. Draw such a line OP, marking its length as 400 mph, and O at the origin. Draw a line PR horizontally to the right and mark it 50. So now you have a ...
January 26, 2017

algebra
What about it?
January 26, 2017

Math
It says the other two angles are equal, so your triangle must be isosceles. Let each of those equal angles be x x + x + 110 = 180 solve for x
January 26, 2017

math
only the 2 or 3 can be used at the front without the odd restriction: number of such number = 2x2x1 = 4 we can actually list them: 345, 354, 435, 453 notice that 1 of them is even so there are only 3 of them or suppose it starts with the 4: only the two odds are left, so ...
January 26, 2017

Maths
Steve did this http://www.jiskha.com/display.cgi?id=1394768509 See other variations of the same question in the Related Questions below
January 26, 2017

Math
the ratio of sides of your triangle are 1:?3:2 or x : ?3x : 2x given x = 16 other sides are 16?3 and 32 perimeter = .... just add them up
January 26, 2017

Math Pre-Calc 12
let the base be x by x cm let the height be y given: 4x + y = 120 y = 120 - 4x V = x^2 y = x^2(120-4x) = 120x^2 - 4x^3 dV/dx = 240x - 12x^2 = 0 for a max of V 12x^2 - 240x = 0 12x(x- 20) = 0 x = 0 ----> yields a minimum volume or x = 20 so the box is 20 cm by 20 cm by 40 cm...
January 25, 2017

Algebra
direction vector of P1P2 = <2 , -2, 0> so the equation of the plane which had <2, -2, 0> as its normal is 2x - 2y + 0z = c but A(1,3,-2) lies on it, so 2(1) - 2(3) + 0 = c c = -4 plane equation: 2x - 2y = -4 or x - y = -2 equation of line through P1P2: x = 2 + 2t y...
January 25, 2017

Math/Algerbra
87 mg needs 4 mL 1 mg needs 4/87 mL 173 mg needs (4/87)(173) mL or appr 7.954 mL or just use a ratio: 87/4 = 173/x 87x = 4(173) x = 4(173)/87 ----> same as above
January 25, 2017

Ap algebra
you can't use the quadratic formula on 2+3X^2-X^3=0 , since it is not a quadratic, it is a cubic Do you have a typo? Assuming it is correct, lets see if it factors: let f(x) = 2 + 3x^2 - x^3 f(1) = 2 + 3 - 1 ? 0 f(-1) = 2 + 3 - (-1) ?0 f(2) = 2 + 12 - 8 ? 0 f(-2) = 2 + 12...
January 25, 2017

Math
Are you using the US gallon or the Imperial gallon? (one of the many problems in not using metric!) I will assume US, so 1 US gallon = 3.97 litres and 1 mile = 1.61 km I will do the 2nd question, you do the first one. 1 gallons ---> 107 miles 3.97 l -----> 107 miles 1 l...
January 25, 2017

Math
number of gallons for each ginger --- 3x cranberry -- 2x orange -- x cost: 2(3x) + 4(2x) + 5x ? 38 19x ? 38 x ? 2 take it from there, remember I said ? .
January 25, 2017

maths
of the 30 fruits, how many are "either grape or banana" ? How many are "not bananas" ?
January 25, 2017

Math
let the width of the lawn be x yds field --- 25 yds by 100 yds area = 2500 yds^2 field including the lawn around it: (25+2x) by (100+2x) yds area = (25+2x)(100+2x) yds^2 area of lawn = (25+2x)(100+2x) - 2500 you said: (25+2x)(100+2x) - 2500 = 2(2500) 2500 + 250x + 4x^2 - 2500...
January 24, 2017

mat
You are given the time it took for the first car to go 599.5 miles in 5.5 hours. Using rate = distance/time the rate of the first car is 599.5/5.5 = 109 mph So the slower car went at 102 mph And the slower car would take 599.5/102 hrs or 5.87745 hrs or 5 hrs and 53 minutes 5:...
January 24, 2017

Math 11
speed of ferry ---- x km/h speed of car ----- x+60 km/h time for ferry = 175/x time by car = 175/(x+60) What are you told about these times? Form your equation from that fact.
January 24, 2017

Math 11
length of squares to be cut out ---- x base ----- 15-2x by 20-2x (15-2x)(20-2x) = 104 solve for x and you have the size of the cut-out The rest is easy
January 24, 2017

Math 11 Foundations
each of the two equal sides ---- x the single side ------- y given: 2x + y = 60 y = 60-2x area = xy = x(60-2x) x(60-2x) = 400 expand, and solve the quadratic
January 24, 2017

Math
3+1/4*cos(theta)=13/4 1/4*cos(theta)=13/4 - 3 = 1/4 cos(theta)= 1 we know cos 0 = 1 so Ø = 0
January 24, 2017

Find the equation of the perpendicular line
steps: - find the midpoint for the given points - find the slope of the line passing through those points - the slope of the line you want is the negative reciprocal of that slope - find the equation using the method you learned.
January 24, 2017

Standard Form
steps: - find the slope of the line passing through the given points - find the equation using the method you learned.
January 24, 2017

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