Saturday
July 23, 2016

Posts by Reiny

Total # Posts: 35,337

math
gibberish! mc023-1.jpg is not an equation, it is a file
June 21, 2016

Maths
Structured method: Let Ron's age be x Terry is x+25 in 5 years: Ron's age = x+5 Terry's age = x+30 x+30 = 2(x+5) x+30 = 2x+10 20 = x Ron is now 20 and Terry is 45 years old
June 21, 2016

math
the vote was 5 to 3, so clearly 8 people voted number opposed is 3 of those 8 or 3/8
June 21, 2016

Math
Can you solve the quadratic: x(2x + 5) = 52 ?
June 20, 2016

Math
To me that says: x^2 - x = 30 x^2 - x - 30 = 0 (x-6)(x+5) = 0 x = 6 or x = -5 your set is {-5, 6}
June 20, 2016

Algebra
looks like 4x3x2 or 24 different ways or nPr P(4,3) = 24 you should have that key on your calculator
June 20, 2016

Geometry
original length -- x original width --- y original height -- z new length ---- x new width ----- y/7 new height --- z/7 original SA = 2xy + 2xz + 2yz new SA = 2x(y/7) + 2x(z/7) + 2(y/7)(z/7) simplify to whatever version you need
June 20, 2016

MATH
My ones digit is 1 ---- xxx1 My tens digit is 2 ore than my ones digit --- xx31 My thousands digit is the difference when my tens digit is subtracted from my hundreds digit ----> 6931 5831 4731 3631 2531 1431
June 20, 2016

math
9988 how easy was that ?
June 20, 2016

math
f(-2) = (-2)^3 + 3(-2)^2 - 2(-2) + 4 = -8 + 12 + 4 + 4 =12 find f(2) and f(0) the same way, then do f(-2) + f(2) - f(0)
June 20, 2016

math
Easy to figure out by looking at the factors of 20 1x20 2x10 4x5 which have a difference of 8 ?? formal way: let one number be x let the other be x+8 x(x+8) = 20 x^2 + 8x - 20 = 0 (x+10)(x-2) = 0 x = -10 or x = 2 if x = 2, the numbers are 2 and 10 if x = -10, the number are -...
June 20, 2016

Math
number correct --- x number incorrect --- 20-x 5x -1(20-x) = 70 5x - 20 + x = 70 6x = 90 x = 90/6 = 15 , as Bob stated
June 19, 2016

math
I assume you want the width of the border. new length = 12+2x new width = 7+2x What has an area of 92 m^2 (you had 92 m) ? if the whole area is 92 m^2 new area = (12+2x)(7+2x) = 92 84 + 38x + 4x^2 = 92 4x^2 + 38x - 8 = 0 2x^2 + 19x - 4 = 0 x = (-19 ± √393)/4 = ....
June 18, 2016

maths
As long as one of the numbers is even, the product will be even So to have an odd product, all of the factors must be odd to have n consecutive odds is (1/2)^n So to have an even would be 1 - (1/2)^n e.g. suppose we roll it three times, n = 3 according to my formula, prob(even...
June 18, 2016

math
Most likely the topic is the Sum and Product of roots of a quadratic for ax^2 + bx + c = 0 sum of roots = -b/a product of roots = c/a given: sum of roots = -3+1 = -2 product of roots = -3 then -(a+1) = -2 a = 1 b/1 = -3 b = -3
June 18, 2016

Math
oil = k(number of buildings)(number of days) o = k bd given: o=6, b=5, d=3 6 = k(15) k = 6/15 = 2/5 oil = (2/5)(bd) 10 = (2/5)(2d) d = 50/4 = 12.5 I agree
June 17, 2016

Algerbra
area of ||gram = base x height so .....
June 17, 2016

math
All your choices are correct except the 2nd look at the terms: 7, 21, 63, 189, 567, ... or 7*1, 7*3, 7*9, 7*27, 7*81 looks like 7* 3^(x-1) btw, that sequence is the one that different from all the others, because it is NOT an arithmetic sequence. For the 20th and 100th term, I...
June 17, 2016

Math
or Just sketch the triangle in II given tanè = -5/1 ----> y/x ---> y = 5, x = -1 r^2 = 5^2+1^1=26 r = √26 sinè = y/r = 5/√26 cosè = -1/√26 tan 2è = 2tanè/(1 - tan^2 è) = -10/(1 - 25) = -10/24 = 5/12
June 17, 2016

Statics
looks rather straightforward ... (62+62+62+x)/4 = 65 186+x = 260 x = 74
June 17, 2016

If alpha
You are probably dealing with the properties of the sum and product of roots of quadratic equations. I will use a and b instead of alpha and beta for 2x^2 - 7x + 3 = 0 the sum of the roots = a+b = 7/2 product = ab = 3/2 so the reciprocals of the roots are 1/a and 1/b new sum...
June 17, 2016

Math
arithmetic sequence with d = 6 and sum of 4 terms = 120 (4/2)(2a + 3d) = 120 2(2a + 18) = 120 2a + 18 = 60 2a = 42 a = 21
June 17, 2016

Math
let the sides be 4x and 7x 8x + 14x = 7 22x = 7 x = 7/22 then 4x = 4(7/22) = 14/11 cm
June 17, 2016

math
(4 √3+5√2)/(√48 +√18) = (4 √3+5√2)/(4√3 +3√2) * (4√3 -3√2)(4√3 -3√2) = (48 - 12√6 + 20√3 - 30)/(48 - 18) = (18 + 8√6)/30 do the second one in the same way. multiply top and bottom by 7 + ...
June 17, 2016

math
a simple way is to find the average of the two numbers for the last one, wouldn't √4 lie between √3 and √5 ? and √4 = 2, so there you have it
June 17, 2016

Calculus
Your 3 strips would be 3 trapezoids. The confusing part is the fact that the last "trapezoid" is actually just a triangle area of trapezoids = (1/2)(1)(6+4) + (1/2)(1)(4+2) + (1/2)(1)(2+0) = 5 + 3 + 1 = 9 ( your area consists of a triangle with a base of 3 and a ...
June 17, 2016

math
I would use a common denominator of 36 take it from there
June 17, 2016

Calculus
If you meant lim x-->0 ((7-3x^5+(x^2)(sinx) )/(5cosx)) then you are right If you meant: lim x-->0 ((7-3x^5+x^(2sinx) )/(5cosx)) I got 8/5
June 17, 2016

calculus
Forget about limits for a while and just consider the simple facts: f(x) = 5 starts at -2 and goes to the left then f(x) = -5 starts at 3 and goes to the right. Those two lines are "linked" by a straight line from (-2,5) to (3,-5) Let's just find that line ..... ...
June 17, 2016

math
if 1 ft corresponds with 1/8 inch then 15 ft correspond with 15(1/8) inches = 15/8 inches or 1 7/8 inches
June 17, 2016

algebra
prob(red) = 12/15 = 4/5 prob(not red) = 1/5 prob( 7 reds of 10) = C(10,7)(4/5)^7 (1/5)^3 = appr .2013
June 16, 2016

Math10
a+3d = 18 a+5d = 28 subtract them: 2d = 10 d = 5 a + 15 = 18 a = 3 now form the first 3 terms
June 16, 2016

geometry
full volume = 14(16)(10) inches^3 = 2240 inches^3 amount which is empty = 2240-1680 = 560 inches^3 percent empty = 560/2240 = .25 or 25% empty
June 16, 2016

Algebra
let the time taken by the robber when he is caught be t hrs distance he covered = 12t miles time taken by the marshall to catch him = t - 1/3 distance traveled by him = 16(t - 1/2) but 12t = 16(t - 1/2) 12t = 16t - 16/2 -3t = -16/2 t = 8/3 hrs
June 15, 2016

Frederick
let each side of one square be x cm let the other have side length y cm so we know: x^2 + y^2 = 100 *** and 4x + 4y = 50 2x+2y=25 ** y = (25-2x)/2 subbing the 2nd part into the first: x^2 + (625 - 100x + 4x^2)/4 = 100 times 4 4x^2 + 625 - 100x + 4x^2 = 400 8x^2 - 100x + 225 = ...
June 15, 2016

Math
Volume = area of base x height 210 = 42 h h = 5 Of course there is an infinite number of possible dimensions. If we are restricted to whole numbers, possible cases could be 6 x 7 x 5 , or 2 x 21 x 5, or 3 x 14 x 5, or 1 x 42 x 5 or 1 x 1 x 210 , or 7 x 3 x 10 , or .....
June 15, 2016

Math
So the angles are x, x, 2x, 3x, 3x, 90 and the sum of all 6 angles in a hexagon is 720 can you take it from here ?
June 14, 2016

math
I assume you are dealing with an AS a+4d + a+23d = 50 2a + 27d = 50 sum of first and 28th = a + a+27d = 2a + 27d = 50 28th term = a + 27d = 50 - a
June 14, 2016

maths
Since the common formula for the amount of an annuity : amount = Payment( (1+i)^n - 1)/i is base on the fact that the payment is made at the end of the period, the only twist that I see in the question would be the first month and the last month. I will also assume that the ...
June 14, 2016

maths
I will use the fact that she deposits $M for the entire period plus and addition $M for the last 15 years, (making it 2M for the last 15 years) i = .06/12 = .005 M(1.005)^480 - 1)/.005 + M(1.005)^180 - 1)/.005 = 1000000 M( 1.005^480 -1 + 1.005^180 - 1)/.005 = 1000000 I get M...
June 14, 2016

math
x(1.05) = 300 x = 300/1.05 = $285.71 What is the meaning of the (2%) ?
June 14, 2016

Business Math
i = .07/12 = .0058333... n = ? 1(1.005833..)^n = 2 log both sides n log 1.005833.. = log 2 n = log 2/log 1.0058333... = 119.17.. months = appr 9 years and 11 months
June 14, 2016

math
I will assume that the second rate was also compounded quarterly quarterly rate for first 5 years = .06/4 = .015 quarterly rate for last 5 years = .045/4 = .01125 amount after first 5 years = 5000(1.015)^20 and after the last 5 years = 5000(1.015)^20 (1.01125)^20 = $8422.90
June 14, 2016

Algebra
A line perpendicular to 7x - 6y = 30 must look like 6x + 7y = c how do you think we can find c ?
June 13, 2016

algebra
Just use the formula, surely you have that in your textbook or your notes.
June 13, 2016

Calculus
Wow, nice problem with very clear and precise instructions how to do it. I suggest you just follow the steps they ask you to perform. I will start you off. Let the finished box be x inches long, y inches wide and 3 inches high given: 3xy = 2760 xy = 920 original piece is (x+6...
June 13, 2016

math
cone = (1/3)π r^2 h where r = 1.5 h = 12 find the volume of the cone, just plug in the values Can = π r^2 h r = 2 h = 2 volume of can = ..... compare to see which is larger. take the difference to see which hold more
June 13, 2016

Pre-Algebra
yes
June 13, 2016

Math
Let AC = x let AB = 2x We can use the cosine law to find x x^2 + (2x)^2 - 2(x)(2x)cos120° = 8^2 5x^2 - 4x^2(-1/2) = 64 7x^2 = 64 x^2 = 64/7 x = 8/√7 perimeter = x+2x+8 = 3x + 8 = 24/√7 + 8 = appr 17
June 13, 2016

Algebra
I think they want the equation in the form ax^2 + bx + c = 0, where a is a positive real number so just "move" all the terms to the left side and set them equal to zero e.g. #5 4x + 3 = x^2 -x^2 + 4x + 3 = 0 x^2 - 4z - 3 = 0 Do the others the same way, it is really ...
June 11, 2016

College Algebra II
The midpoint of (a,b) and (c,d) is ( (a+c)/2 , (b+d)/2) ) let P2 be (c,d) for the x value : (c + (-2) )/2 = -1 c -2 = -2 c = 0 find the y value of P2 in the same way. Check by finding the midpoint of P1 and P2 using the formula I gave, and make sure you get the point (-1,3)
June 11, 2016

Math
A = {2,3,5} and B = {1, 3, 5} 2+1 = 2+3 = 2 + 5 = 3+1 = 3+3 = 3+5 = 5+1 = 5+3 = already have that 5+5 = make sure you don't count equal sums twice, e.g. 3+3 = 6 5+1 = 6 You are just looking at the different sums
June 11, 2016

Math
no in a phase shift, the shape of the sine curve does not change, but in a period change you are changing the shape
June 11, 2016

Math
Did you mean that 3 of the angles are in the ratio of 2:3:7 ? let those three angles be 2x, 3x, and 7x let the fourth angle be y 2x + 3x + 7x + y = 360 y + 12x = 360 y = 360 - 12x "the mean of these angles is 64" I will assume you mean the mean of the 3 angles. 12x/3...
June 11, 2016

Math
x^2 + 13x - 30 = 0 (x-2)(x+15) = 0 x = 2 or x = -15 which is the smaller ?
June 11, 2016

Math
original fraction: x/(x+4) new fraction = (x+3)/(x+7) (x+3)/(x+7) = 3/4 4(x+3) = 3(x+7) solve for x, and sub back into original fraction
June 11, 2016

math
ummmh, so the sum is 18 made of 6 equal digits?? What do you think?
June 11, 2016

algebra
Just stating the answer is not helping Tourille learning how to do this.
June 11, 2016

Calculus
Let one of them be x, and the other one y xy = 2 y = 2/x sum = x+y = x + 2/x d(sum)/dx = 1 - 2/x^2 = 0 for a min sum 1 = 2/x^2 x^2 = 2 x = √2 , then y = 2/√2 = √2 their minimum sum = x+y = √2 + √2 = 2√2
June 10, 2016

Math
tried to find a relation, could not find a definite one. the graph looks almost linear. http://www.wolframalpha.com/input/?i=pattern(100,+105,107,110,+115,120,123,126) (I used units of 1000) What is your depth of study of this? Have you learned about "equations or lines ...
June 10, 2016

Math
What are we finding? The equation? let y = kx for the given values: 3 = 7k k = 3/7 so y = (3/7)x or x = (7/3)y or y/x = 3/7 or y : x = 3 : 7 etc
June 10, 2016

Algebra 1
slope = (y2 - y1)/(x2 - x1) = (2-4)/(3-(-4) ) = .....
June 10, 2016

Math (pre-celc 12)
since you labelled this "pre-calculus" , I suppose we can't use the derivative, which would be the easiest way of doing it consider: y = 6 cos( (2π/14)x) the period = 2π/(2π/14) = 14 You had that. so we have a cosine curve with a max of 6 when x = ...
June 10, 2016

Algebra
You know that the equation in the form y = mx + b has to be y = (7/3)x + b plug in the given point: 11 = (7/3)(3) + b 11 = 7 + b b = 4 y = (7/3)x + 4
June 9, 2016

MATH
Thank you Ms Sue.
June 9, 2016

MATH
You sure got me on that "were" vs "where". As to education vs dancing, you are absolutely free to set your priorities.
June 9, 2016

Dear Mom - MATH
Sorry to say this, but if you are homeschooling your child and you are "completely lost" with this routine question, perhaps it is time to send him/her to a regular school were qualified math teachers can do it. both Steve and I have both answered this question, ...
June 9, 2016

ALGEBRAA
I have seen this same question about 4 times now Steve just answered it for you here: http://www.jiskha.com/display.cgi?id=1465520203 You even thanked him. Why are you repeating it ?
June 9, 2016

Math
why are you switching names? http://www.jiskha.com/display.cgi?id=1465510795
June 9, 2016

math
suppose we have f(x) = 3x^3 - 5x^2 + 4x + 1 and we divide that by x-2 ( I can't show the long algebraic division in this format, but I am sure you know how to do that) you should have 3x^2 + x + 6 with a remainder of 13 now let's find f(2) f(2) = 3(8) - 5(4) + 4(2) + 1...
June 9, 2016

math
What have you got so far for this assignment? You didn't expect me to just do it for you, did you?
June 9, 2016

algebra
Did you mean it the way you typed it, then by the order of operations.... x + 1x= b/x, since a/a = 1 2x = b/x 2x^2 = b x^2 = √(b/2) for extraneous roots, a can be any non-zero number, and b < 0 If you meant: (x+a)/(ax) = b/x x^2 + ax = abx x^2 + ax - abx = 0 x^2 + x(a...
June 9, 2016

ALGEBRA
Do you have a programmable calculator such as TI which does graphs? How do you expect me to do this for you ? There are all kinds of suitable webpages that will do graphs for you. This one is one of the best: http://www.wolframalpha.com/input/?i=plot+y+%3D+(3x+-+4)%2F(x+%2B+2...
June 9, 2016

ALGEBRA
how about y = (3x - 4)/(x + 2)
June 9, 2016

Math(Please Help Assignment Due)
look back when you first posted this
June 9, 2016

Parametric Equations
I would have chosen that one too
June 9, 2016

Algebra
ummmhhh, yes
June 9, 2016

Algebra
y = x^2 + 3x + 5 y = x + 13 solution: x^2 + 3x + 5 = x + 13 x^2 + 2x -8 = 0 (x+4)(x-2) = 0 x = -4 or x = 2 if x = -4, y = 9 if x = 2 , y = 15 http://www.wolframalpha.com/input/?i=plot+y+%3D+x%5E2+%2B+3x+%2B+5,+y+%3D+x+%2B+13
June 9, 2016

Math2
-think of a number ----- x - triple it -------------- 3x - add 6 ---------------3x+6 - divide by 3 ---------x+2 - add 5 -------------- x+7 - subtract your original number -------- 7 Paula now knows the number Jessica ended up with. always 7 !
June 9, 2016

Math
First of all, where does the first line come from? if it is true, then 7(a+b)-5(a+b)=7c-5c 2(a+b) = 2c a+b = c a+b-c = 0 so in your second last line you divided by zero, which is a mathematical No No. any subsequent conclusion you draw would be bogus.
June 9, 2016

Logic and Reasoning
You have to have brackets for your conjecture to be true 15/20 = 3/4 , then (15-3)/(20-4) = 12/16 = 3/4 18/15 = 6/5, then (18-6)/(15-5) = 12/10 = 6/5 suppose a fraction a/b is not in lowest terms and can be reduced to c/d then a/b = c/d = k is (a-c)/(b-d) = k ?? from c/d = k, ...
June 9, 2016

trigonometry
ahh, the old "missing bracket" trap. Thanks Steve.
June 8, 2016

trigonometry
I will write it as: (cosx + cosy)² + (sinx + siny)² = 4cot(x-y/2) --> easier to type LS = cos^2 x + 2cosxcosy + cos^2 y + sin^2 x + 2sinxsiny + sin^2 x = sin^2 x + cos^2 x + sin^ y + cos^2 y + 2(cosxcosy + sinxsiny) = 2 + 2cos(x - y) = 2(1 + cos(x-y) ) RS = 4 cot(...
June 8, 2016

Math
You should know that the volume of a cone = (1/3)π r^2 h Just plug in your data
June 8, 2016

Math
No algebra or variables needed here. Just do the arithmetic. "Harry has $120. Harry has 3 times as much money as Tom" ---> so Tom has $40 "Tom has twice as much money as Gabi" ----> Gabi has $20
June 8, 2016

statistics
z-score = ( X - mean)/sd z-score = (95-80)/10 = 1.5
June 8, 2016

Math
The last part of the sentence " if it is known that tails occurs at least twice?" contradicts the first part. ignoring that last part we would have: C(4,3)(1/2)^3 (1/2) = 4 (1/16) = 1/4
June 8, 2016

Trigonometry
Did you make your sketch? You have a triangle with all sides known, a clear case of the cosine law, let the angle between them be Ø 189^2 = 244^2 + 168^2 - 2(244)(168)cosØ 2(244)(168)cosØ = 244^2 + 168^2 - 189^2 cosØ = (244^2 + 168^2 - 189^2)/(2(244...
June 8, 2016

math
let n be the number he originally bought cost = 20(n/50) = 2n/5 number he sold = n-30 return = 1.2(n-30) profit equation: 1.2(n-30) - 2n/5 = 84 1.2n - 36 - 2n/5 = 84 1.2n - .4n = 120 .8n = 120 n = 150 he bought 150 tomatoes check: cost to buy them = 20(150/50) = $60 return = 1...
June 8, 2016

Math
3n - 12 = 30 3n = 42 n = 42/3 or 14 years
June 8, 2016

Math
no, look at how "an apple is 10% lighter ..." became .9 so what percentage do I need to have .8333... ?
June 8, 2016

Math
g = 1.08 o -----> o = g/1.08 a = .9 o ---> o = a/.9 g/1.08 = a/.9 .9 g = 1.08a a = (.9/1.08) g a = .8333... g state your conclusion.
June 8, 2016

Math
What changes do you think you have to make in my solution? http://www.jiskha.com/display.cgi?id=1465418863
June 8, 2016

Pre-Calculus Matrix
never mind the matrix stuff. Suppose we subtract #3 - #1 I get x + 4y + 6z = 8 but #2 says: x + 4y + 6z = -32 which contradicts the above, so .... no solution
June 8, 2016

Math
yes
June 8, 2016

Math
how did you get that? Are we including the area of the base ?
June 8, 2016

math
if you want the eastward displacement ... x/50 = cos 10° x = .....
June 8, 2016

Math
I think you missed my point. I was pointing out that there is no octagon possible with sides of 19 and apothem of 16. Carefully read what my explanation said. Thus, none of the answers make any sense. Please let your teacher know, so he/she can correct the worksheet. Just ...
June 8, 2016

Math
There is a problem with your question. You said it was a regular octagon with sides 19 inches, forget the apothem part right now. Then you have 8 equal isosceles triangles with an angle of 360/8 or 45° at the top and angles of 67.5° at each of the bases. The height of ...
June 8, 2016

Math
in general if the centre is (h,k), the equation is (x-h)^2 + (y-k)^2 = r^2 notice that the sign inside the bracket is opposite to the sign used in the given point. so for (-4,-3) it must be (x-(-4) )^2 + (y - (-3) )^2 = r^2 (x+4)^2 + (y+3)^2 = r^2 to find the r^2, just plug in...
June 8, 2016

  1. Pages:
  2. <<Prev
  3. 1
  4. 2
  5. 3
  6. 4
  7. 5
  8. 6
  9. 7
  10. 8
  11. 9
  12. 10
  13. 11
  14. 12
  15. 13
  16. 14
  17. 15
  18. Next>>