Thursday
February 11, 2016

Posts by Reiny

Total # Posts: 32,954

math
Sounds like a boring football game.
February 11, 2016

Algebra 2
if x-2 is a factor, then x = +2 has to make the expression equal to zero if x+2 is a factor, then x = -2 has to make the expression equal to zero try it ... then use the same concept for the other cases.
February 11, 2016

Algebra
Two strikes (4/7y^5)^2 = (4/7y^5)(4/7y^5) = (16/49) y^10 (x/2y^5)^-2 = (2y^5/x)^2 = 4 y^10 / x^2
February 11, 2016

MATH
Each side is √122 cm I know √121 = 11 so the side is appr 11 cm and the perimeter would be appr. 44 cm (actual answer = 44.18...)
February 11, 2016

Geometry
A Pythagorean triple consists of 3 whole numbers a, b, and c such that a^2 + b^2 = c^2 ---> that's the Pythagorean Theorem e.g. a = 5, b=12, and c=13 is one of them because 5^2 + 12^2 = 13^2 25 + 144 = 169 169 = 169 If you randomly pick any such 3 numbers, the vast ...
February 11, 2016

college algebra
did you mean? y = 1/(x^2 + 9) since it doesn't matter if you use +x or -x, we have symmetry about the y-axis
February 11, 2016

college algebra
translated into Math .... (8+√-12)-(4+2√3 i) = 8 + 2√3 i - 4 - 2√3 i = 4 aside: √-12 = (√-1)√12 = i √4 √3 = 2√3 i
February 11, 2016

math
I would triple the first one: 15x + 6y = 66 -2x + 6y = 3 subtract them: 17x = 63 x = 63/17 back into original first: 5(63/17) + 2y = 22 2y = 59/17 y = 59/34 check them in the original equations, it works
February 11, 2016

Math
let the 4 even's be x , x+2, x+4, and x+6 their sum = 8484 take over....
February 11, 2016

Math
Tom's age now ---- x , where x < 10 Chris' age now = 2x 8 years from now: Tom --- x+8 Chris --- 2x+8 x+8 = (3/4)(2x+8) 4x + 32 = 6x + 24 -2x = -8 x = 4
February 11, 2016

math
One side needs 16 tiles (visualize placing 4 tiles by 4 tiles) He will cover 5 of the faces, so ......
February 11, 2016

Math
When they meet, they will have traveled for the same time. Let that time be t hrs. let the distance covered by the fast train be x miles, then distance covered by the slower train is 90-x time for faster train = x/90 time for slower train = (90-x)/45 x/90 = (90-x)/45 45x = ...
February 11, 2016

Algebra
nope Did you sub in the values of x given ? I just did two of them when x = 3, f(3) = 11 when x = 1, f(1) = 3 none of a), b), or c) have those correct, so we rule out those three answers. Mmmmhhh, wonder what that leaves.
February 11, 2016

Algebra
is x a variable or a multiplication sign ? You can't have it both ways.
February 11, 2016

Algebra
Time needed = (500-120)/60 What's with all this "model the problem" stuff. You make a statement such as Time needed = (500-120)/60 work it out, and you are done. You had that, good job Introducing variables like x is not necessary, and asking for an "...
February 11, 2016

math 035
length --- x width ----x/2 + 3 x(x/2 + 3) = 140 x^2 /2 + 3x - 140 = 0 x^2 + 6x - 280 = 0 (x - 14)(x + 20) = 0 x = 14, we reject the x = -20 length is 14 m, width is 10 m
February 11, 2016

correction - MATH
You are "choosing" 3 from 9 The answer of 504 represents the number of permutations, that is, there are distinct places. e.g. ABC is different from BAC This is a combination question number of ways to choose 3 from 9 = C(9,3) = 84 C(9,3) = 9!/(3!6!)
February 11, 2016

math
prob(greater than two) = 4/6 = 2/3 prob(not greater than two) = 1 - 2/3 = 1/3
February 11, 2016

math
area = (1/2) base x height (1/2)(12)h = 72 6h = 72 h = 12
February 11, 2016

math
you are right. Since 42 gallons is 6 times the 7 gallons he will go 6 times as far 6(172) = 1032
February 11, 2016

Math
outside volume = 36(25)(16.5) cm^3 = 14850 cm^2 volume of inner part (the empty space) = 33(22)(13.5) cm^2 = 9801 cm^3 volume of iron = 14850 - 9801 = 5049 cm^3 1 cm^3 weighs 7.5 kg so weight of box = .....
February 11, 2016

Math
did you make a sketch? If so, you should see the ratio ... h/7.5 = 1.5/4.5 h = 7.5(1.5)/4.5 = ...
February 11, 2016

Math
The simpler rule is : add 1 so the terms are: 7, 8, 9, ...
February 10, 2016

College Algebra
Is there a question in this story? I assume you want to know the height of the flagpole. Since we have similar triangles, use a simple ratio .... h/36 = 6/4 etc
February 10, 2016

College Algebra
let the number of $1 increases be n number of tickets sold = 1000 - 60n price per ticket = 17 + n Receipts = (17+n)(1000-60n) expand and collect like terms Set this equal to 16400 and solve using the quadratic formula
February 10, 2016

Math - Could Someone Check My Work?
6x^6 ∙ 6x^6 = 36^12 Your answer is wrong, should be 36x^12 looks like you missed the x and for some reason I thought you multiplied the bases of 6 and added the exponents. In the last question, the last = sign is just a stray one hanging around, ignore it.
February 10, 2016

Math - Could Someone Check My Work?
(14a^2b)(2ab^2c) = 28a^3b^3c ✔ (a^25)^7 = a^125 ✔ 6x^6 ∙ 6x^6 = 36^12 no, keep the base and add the exponents = 6^12 or multiply the bases and keep the same exponent = 36^6 (2x^2)^3 = 8x^6 ✔ (-2)^0 = 1 ✔ 30x^20/(6x^9 = 5x^11 ✔ 4x^5 &#...
February 10, 2016

Mathematics
good work, for better form, place equal signs in front of each new line You are saying "What I am about to write is equal to the previous line" 6(11-(4)^2+3 = 6(11-16+3) = 6(-5+3) = 6(-2) = -12
February 10, 2016

Math
I assume you are solving add them the way they sit 6x = 12 x = 2 sub that into the 2nd , or the 1st. I usually sub into the easier looking one.
February 10, 2016

correction - Algebra
I think you meant: When 3x^2 – 2x + 1 is subtracted from 2x^2 + 7x + 5, the result will be what? so 2x^2 + 7x + 5 - (3x^2 - 2x + 1) = 2x^2 + 7x + 5 - 3x^2 + 2x - 1 = -x^2 + 9x + 4
February 10, 2016

Algebra
7x^2 - 4x - (5x^2 + 2x) = 7x^2 - 4x - 5x^2 - 2x = 2x^2 - 6x do the 2nd the same way
February 10, 2016

math - please help!!
Did you realize that the initial direction of the ship to the lighthouse and its direction of travel form a 90° angle ? So we have a right-angled triangle. Entering your data in my diagram, I found the angle I need to be 24.67° and cos24.67 = 10.8/x, where x is the ...
February 10, 2016

math
I read that as (x,y) ---> (x-6,y+2) followed by (x,y) ---> (x+3, y + 1) so: (x,y) ---> (x-6,y+2) ---> (x-6 + 3,y+2 + 1) or (x,y) ----> (x-3, y+3)
February 10, 2016

Math
Your scale factor has no units , so we can put in any units we want. how about 1 foot : 250 ft or 12 inches : 250 ft 12/250 inches : 1 ft 1200/250 inches : 100 ft 4.8 inches : 100 ft 1 inch : 100/4.8 ft 1 inch : 20.83 ft or 12/250 = x/100 250x = 1200 x = 4.8 so 4.8 ft ...
February 10, 2016

Math
# of P5 --- x # of P1 --- x+2 # of P10 -- x+2 + 1 = x+3 equation dealing with "value" 5x + x+2 + 10(x+3) = 112 finish it up.
February 10, 2016

Math
I did this one this morning http://www.jiskha.com/display.cgi?id=1455114875
February 10, 2016

Geometry
That should have said: 6 square inches and 24 square inches area1/area2 = (side1)^2 / (side2)^2 6/24 = side1^2/side2^2 1/4 = side1^2/side2^2 side2^2 = 4side1^2 take √ side2 = 2 side1 the scale factor is 1 : 2
February 10, 2016

Math
If he started with $x amount left after foodcourt = (3/4)x amount left after ride = (1/3)(3/4)x = (1/4)x so (1/4)x = 10 x = $40
February 10, 2016

math
let's look to see if we can find a pattern 1-2 >>> 1x2 2-6 >>> 2x3 3-12 >>>3x4 4-20 >>> 4x5 ... looks like if n is the shelf number, then the number of books is n(n+1) so on the 10th shelf, there would be 10x11 or 110 books Sure hope ...
February 10, 2016

math
(x,y) ---> (x-2, y-1) then (x-2,y-1) --> (x-2 + 5, y-1 + 6) or (x,y) ---> (x+3, y+5) illustrate by picking any point and seeing what happens.
February 10, 2016

Math
solve for x .28 x = 168 x = 168/.28 = ...
February 10, 2016

math
x - 5 ≤ 20 "at most" means it can't go over 20, so it has to be less than. Your expression said > 20 Furthermore, by saying the difference between a number and 5, you don't say which way we are subtracting. e.g. if I say what is the difference ...
February 10, 2016

math
Just did it when you were Tommy http://www.jiskha.com/display.cgi?id=1455143548
February 10, 2016

i need help please math
reflection in the y-axis (x,y) ---> (-x,y) reflection in the x-axis (-x,y) ---> (-x, -y) so (x,y) --> (-x,-y) , which is a reflection in the origin. pick a point and illustrate it on a grid. e.g. watch what happens to (3,5)
February 10, 2016

Math PLEASE HELP
Just add them up, then divide by 10. That would be just like finding the average. Hint: change them to decimals, they all come out nice that way, simpler to add them that way e.g. 4 ¼ kg = 4.25 kg
February 10, 2016

Mathematics
look at my attempt here http://www.jiskha.com/display.cgi?id=1455132924
February 10, 2016

Cal 2
V = π ∫(9/x^2) dx from x=3 to 5 = π( -9/x) | 3 to 5 = π(-9/5 - (-9/3) ) = π(6/5) = 1.2π cubic units
February 10, 2016

Algebra
Well, you got it 4t^2 - 20t - 150 = 0 by the formula t = (20 ± √2800)/8 =9.11 or a non-admissible negative value
February 10, 2016

Maths
x^2+2xy+2y^2+6y = x^2+2xy+y^2 + y^2+6y = (x+y)^2 + y(y+6) = S x _ y _ S 0 0 0 1 0 1 2 0 4 3 0 9 4 0 16 ... 0 1 8 0 2 20 .. -------no future here, S gets bigger try negative values 0 -6 36 1 -6 25 .. 5 -6 1 5 -5 -5 1 -1 -5 2 -2 -8 3 -3 -9 <-------- LOOKS LIKE THAT IS IT 4 -4...
February 10, 2016

Geometry
I assume that you have listed the two triangles in matching vertices, that is, A <--> D , etc let AB = 2x then DE = 3x , must be in the ratio of 2:3 if AB = 2BC 2x = 2BC BC = x given: DE = 3BC DE = 3x , (we already knew that) then EF = 6x
February 10, 2016

Math
I will assume you mean m^9t^-10/(m^-4t^-5) = m^13 t^-5 or m^13/t^5 you are correct
February 10, 2016

Cal 2
no need for calculus. your solid is a fulcrum formed by the following: You have a cone on its side, (the x-axis is the axis of the cone) height = 3, radius = 9 the other : height = 5, radius = 15 V = (1/3)π(15^2)(5) - (1/3)π(9^2)(3) = (1/3)π (1125 - 243) = 882&#...
February 10, 2016

math
$1,4000 ?? I assume you meant $1,400 what is .65(1400) ?
February 10, 2016

algebra
complex roots always come in conjugate pairs, so we have x = -3i and x = 3i two factors are (x + 3i) and (x- 3i) (x+3i)(x-3i) = x^2 - 9i^2 = x^2 + 9 Using long algebraic division, you should get ( 3x^4+5x^3+25x^2+45x-18) ÷ (x^2+9) = 3x^2 + 5x + 2 the quadratic formula ...
February 10, 2016

math
Using the basic definitions: a + 4d = -12 a + 9d = 27 subtract them 5d = 39 d = 39/5 or 7.8 sub back in .... a+4(7.8) = -12 a = -43.2 sequence is: -43.2 , -35.4, -27.6, -19.8, -12, ... term15 = a + 14 d = ..... B) The first three terms of an A. P are x and the 10th term. That ...
February 10, 2016

Math
My crystal ball does not seem to be working today. I just can't seem to conjure up your parallelogram.
February 10, 2016

Cal 2
Just did this http://www.jiskha.com/display.cgi?id=1455128294
February 10, 2016

Cal 2
no Calculus needed. extend the sides to form the original cone. let the height of the added cone be h by ratios h/13 = (h+25)/30 30h = 13h + 325 17h = 325 h = 325/17 volume of fulcrum = (1/3)π(30^2)(25 + 325/17) - (1/3)π(13^2)(325/17) = (1/3)π[900(25+325/17) - ...
February 10, 2016

math
basic trig: sinØ = 5/8 = .. Ø = appr 38.7°
February 10, 2016

Algebra 2
from the first: y = -2x-11 into the 2nd 3x - 4(-2x-11) = 11 3x + 8x + 44 = 11 11x = -33 x = -3 No need to find y, the only one with x=-3 is the third one. To make sure, sub (-3,-5) into both equations.
February 10, 2016

Math
solve: 15m = 5m + 1100
February 10, 2016

maths class8
see your previous post
February 10, 2016

maths
now: son --- x father -- 5x 5 years ago: son = x-5 father = 5x-5 5x-5 = 7(x-5) solve for x
February 10, 2016

algebra
I started with x = ±1 and got x= 1 so (x-1) is a factor and also found x = ±2 to work so (x+2)(x-2) were factors so x^4+6x^3-11x^2-24x+28 = (x-1)(x-2)(x+2)(x .... ?) so far my constant multiply to get 4, but I need +28, so the last digit must be +7 x^4+6x^3-11x^2...
February 10, 2016

let's try again - Math
oops, just noticed my third equation is wrong Here we go again: I will use the notation a = (2,-1,1) , b= (1,-3,1) , c=(-2,1,-3) and d=(3,2,5) so 2p + q - 2r = 3 -p - 3q + r = 2 p + q - 3r = 5 add the 2nd and 3rd: -2q - 2r = 7 2q +2r = -7 ** double the 2nd , then add to the ...
February 10, 2016

Math
I will use the notation a = (2,-1,1) , b= (1,-3,1) , c=(-2,1,-3) and d=(3,2,5) so 2p + q - 2r = 3 -p - 3q + r = 2 -2p + q - 3r = 5 add 1st and 3rd: 2q - 5r = 8 ** double the 2nd , then add to the first: -5q = 7 q = -7/5 into ** -14/5 - 5r = 8 -5r = 54/5 r = -54/25 into the 1st...
February 10, 2016

Math
number of P5's --- x number of P1's --- y x+y = 16 5x + 1y = 44 subtract them: 4x = 28 x = 7 y = 9 check: 5(7) + 1(9) = 44
February 10, 2016

math
Case1: the number of hours is single digit hours --- h unit digit of minutes --x tens digit of minutes --y x+10y = 5h ** x+y+h = 15 h = 15-x-y 5h = 75 - 5x-5y *** equating ** and *** x+10y = 75-5x-5y 6x + 15y = 75 2x + 5y = 25 x = (25-5y)/2 --> 25 - 5y must be even so it ...
February 10, 2016

Trigonometry
Once you make your diagram, it is easy to see that we can use the cosine law. AC^2 = 560^2 + 320^2 - 2(320)(560)cos104° = 502704.8074 AC = appr 709 miles
February 10, 2016

algebra
f(g(-7)) = f(-14-6) = f(-20) = 60-4 = 56
February 9, 2016

Mathh
5 marbles out of 12 Prob(red) = 5/12
February 9, 2016

math
yes, but usually a unit of 1 is used 2.5 inches : 79 miles 1 inch : 79/2.5 mile 1 inch : 31.6 miles If you use the same units, they can be skipped in the scale ... 31.6 miles = (31.6)(12)(5280) inches 2002176 inches so you could state the scale as 1 : 2,002,176
February 9, 2016

mathemathics
Just did this in your earlier post of this.
February 9, 2016

math
let the unit digit be x then the hundred digit is 2x let the tens digit by y so the number is 100(2x) + 10y + x = 201x + 10y the number reversed is 100(x) + 10y + 2x = 102x + 10y 201x+10y - (102x+10y) = 396 99x = 396 x = 4 looks like y can be any digit from 0 to 9 the original...
February 9, 2016

MATH
let the angles be 3x and 2x their sum = 90° 5x = 90 x = 18 the smaller angles is 2x = 36°
February 9, 2016

Math
I attempted this question yesterday. Had some doubts about the typing http://www.jiskha.com/display.cgi?id=1454969855
February 9, 2016

shelby
rise --- x m hypotenuse -- x+32 run --- x+31 x^2 + (x+31)^2 = (x+32)^2 x^2 + x^2 + 62x + 961 = x^2 + 64x + 1024 x^2 - 2x - 63 = 0 (x-9)(x+7) = 0 x = 9, or x = -7 which would be silly the sides are 9, 40, and 41 check: 9^2 + 40^2 = 41^2, true!
February 9, 2016

algebra
L = k(1/d^2) for the given: 75 = k(1/225) k = 16875 L = 16875/d^2 then if d = 47 L = 16875/47^2 = 7.6 decibels
February 9, 2016

college algebra
b) .12x c).15y d) your equation should say .12x + .15y = 64500 times 100 12x + 15y = 6450000 divide it by 3 4x + 5y = 2150000 first equation times 4 4x + 4y = 2000000 subtract them: y = 150,000 then x = 350,000 check: .12(350000) + .15(150000) = 64500
February 9, 2016

algebra
"Type your answer in the box provided "... tells me that you simply want us to do your assignment for you. This question is of such fundamental nature, that you absolutely MUST know how to do it. What are your steps so far ?
February 9, 2016

Cal 2
the x-intercepts for both functions are c and -c If you look at your sketch there is symmetry about the y-axis as well, so we could just take our area from 0 to c 4∫(c^2 - x^2) dx = 230 from 0 to c ∫(c^2 - x^2) dx = [c^2 x- (1/3)x^3] from 0 to c = (c^3 - (1/3)c^3...
February 9, 2016

algebra
the simplest right-angled triangle has sides 3,4, and 5 If you did not know that, let the three sides be x, x+1, and x+2 x^2 + (x+1)^2 = (x+2)^2 x^2 + x^2 + 2x + 1 = x^2 + 4x + 4 x^2 - 2x - 3 = 0 (x-3)(x+1) = 0 x = 3 or x = -1, the last one is silly x=3 conclusion ....
February 9, 2016

Math- Calc
done, look back a few posts
February 9, 2016

Algebra
(6x^-2)^2(0.5x)^4 = (36x^-4)(1/16)(x^4) = 36/16 x^0 , but x^0 = 1 = 36/16 = 9/4
February 9, 2016

Algebra
at the x-intercepts, y = 0 , so ... x^2 + 0 + 8x - 0 - 49=0 using completing the square: x^2 + 8x +16 = 49+16 (x+4)^2 = 65 x+4 = ±√65 x = -4 ± √65 or appr 4.06 or appr -12.06 confirmation. Notice your equation represents a circle http://www....
February 9, 2016

Math
f(x) = |(x+9)(x-7)| the function y = (x+9)(x-7) would have x-intercepts at -9 and 7 , and it would dip below the x-axis between these two values. So the |...| flips that part above the x-axis, causing CUSPS at x =-9 and x=7 the derivative does not exist for those two values.
February 9, 2016

Maths
I will assume you meant to say: The first term of an arithmetic sequence is 23 and the 12th term is 72. So a = 23 , and a+11d = 72 23+11d = 72 11d = 49 d = 49/11 take over, all you have to do is use the formulas
February 9, 2016

algebra equations
Bosnian, you are correct if the number is 31/6 then 31/6 + 5(31/6) - 4 = 31/6 + 155/6 - 4 = 31-4 = 27
February 9, 2016

Math
if you want the prob of a 5 OR a 6 OR an odd, then it would be 4/6 = 2/3 If you want the prob of a 5 AND a 6 AND an odd, then it would be 0
February 9, 2016

Math
Not clear if the new monies are transferred from the other person's wallet, or if they are new monies. e.g. Do the 80 cents that Cheryl puts in her wallet come from Sally? Please clarify.
February 9, 2016

math
number of plates = 10x10x10 x 26x26 = 676,000
February 9, 2016

Math
just add them 4y = 28 y = 7 sub back into the 2nd x - y = 15 x - 7 = 15 x = 22
February 8, 2016

optional math
for AP first -- a fourth --a+3d ninth -- a+8d these are to be in GP (a+3d)^2 = a(a+8d) a^2 + 6ad + 9d^2 = a^2 + 8ad 9d^2 - 2ad = 0 d(9d -2a) = 0 d = 0 or a = 9d/2 reject d=0, because the sequence simply becomes a, a, a, .... which technically is an AP as well as a GP if a = 9d...
February 8, 2016

Math
From the many ways your ambiguous way of typing could be interpreted , I will choose (16x-12)/(4x^2+5x-6) - 3/(x+2) = 4(x-3)/( (x+2)(4x-3) ) - 3/(x+2) = (4(x-3) - 3(4x-3))/((x+2)(4x-3)) = (4x - 12 - 12x + 9)/((x+2)(4x-3)) = (-8x - 3)/((x+2)(4x-3))
February 8, 2016

Maths
make a sketch to see that the 10.5 cm becomes the hypotenuse of the cone and the circumference of the cone is the arc length of the sector. 160° = 160/180π radians = 2.7925.. radians arc = 2.7925(10.5) = 29.32153.. this becomes the circumf of the base of the cone 2&#...
February 8, 2016

Algebra
time = distance/rate 90 miles/hour = 90(5280) ft / 3600 seconds = 132 ft/s so time = 60.5 ft/132 ft/s = .45833... seconds = appr .46 seconds
February 8, 2016

Geometry
your value of a is correct. Actually your given triangle is a 30-60-90 right-angled triangle with sides in the ratio 1 : √3 : 2 = 50: 50√3:100 You didn't say which of the legs is the x and the other the y. Assume the x is opposite the 30° angle then the ...
February 8, 2016

pre-calculus
your x(x-3)<2 or x(x-3)<2 are the same expression did you mean: x(x-3)<2 or x(3-x)<2 ? some preliminary... clearly any negative value of x will work, since -(+) is negative which is < 2 notice that is true for all x < 1 so x < 1 also if x = 2, we have 2|-1...
February 8, 2016

math
(3^x)(5^x) + 1 = 20 (15)^x = 19 use logs x log15 = log 19 x = log19/log15 = appr 1.08729 Use your calculator to check, it works
February 8, 2016

Math
areas of similar shapes are proportional to the square of their corresponding sides ratio of their areas is 2^2 : 3^2 = 4 : 9
February 8, 2016

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