Sunday
February 26, 2017

Posts by Reiny

Total # Posts: 37,803

math
How many 5's do you see on 1 die ??
February 18, 2017

Algerba
Well, why don't we solve it, probably faster than subbing in all those values -1.5^2+4x+2.2=0 3x^2 - 8x - 4.4 = 0 x = (8 ± ?116.8)/6 = appr 3.13 or -.5 you are right
February 18, 2017

maths
list the first prime numbers, add them up, then divide by 10 remember the first prime number is 2, then 3, etc
February 18, 2017

Algebra I
4p - 2m = 2 ---> 2p - m = 1 or m = 2p-1 3p + 9m = 54 sub in m=2p-1 into the other equation and solve
February 18, 2017

math
how many kings ? how many hearts ? remember not to count the king of hearts twice, it would be included in both counts.
February 18, 2017

maths
so you have 2/5 left (2/5)x = 80 2x = 400 x = 200 check: take 3/5 of 200 and subtract it from 200. What do you have left ?
February 18, 2017

@ Steve - MATH
Nice!!! Well, I always like to take those long detours. I once went from Toronto to Niagara Falls by going all the way around Lake Ontario.
February 18, 2017

MATH
cos 4A = cos^2 2A - sin^2 2A = (cos 2A - sin 2A)(cos 2A + sin 2A) = (cos^2 A - sin^2 A - 2sinAcosA)(cos^2 A - sin^2 A + 2sinAcosA) from cosA = 1/2 ----> sinA = ?3/2 (A = 60° or ?/3) plug the cos and sin values into my last equation and evaluate, I will leave the ...
February 18, 2017

math
(1/3)p = 2 p = 6
February 18, 2017

Geography
The angle between is 150° which is 150/360 or 5/12 of a rotation. 5/12 of 24 hours is 10 hours. so the time would be 5:30 - 5:00 = 19:30 ---> evening of previous day ( that would be 7:30 pm using US notation) time decreases from east to west
February 18, 2017

algebra 2
my starting equation would be: y-5 = -1(x+3) re-arrange it to see which one fits
February 17, 2017

Algebra 1
What makes you "think" it is either a or c What did you do to get the answer?
February 17, 2017

algebra
What are you doing ???? (4275)(4372) = 18,690,300
February 17, 2017

math
your number ---- x x/4 + 5 - 6 = 6 x/4 = 7 multiply both sides by 7 x = 28 try it.
February 17, 2017

math
I think that should be 48 done 6 years ago by MathMate http://www.jiskha.com/display.cgi?id=1307634385
February 17, 2017

math
you have posted 4 disconnected statements 215 = 0.73n ----> false n = 0.73 × 215 ----> does not follow from the previous, but would be correct 0.73 = n × 215 -----> does not follow from the previous 215 = 73n ---> does not follow the previous, but ...
February 17, 2017

Math
suppose we use an example: e.g. f(x) = (x-5)^2 + 3 , which is a parabola with vertex (5,3), opening upwards f(2-x) = (2-x - 5)^2 + 3 f(2-x) = (-x - 3)^2 + 3 f(2-x) = (x+3)^2 + 3 , (just like (-9)^2 = 9^2 ) -f(2-x) = -(x+3)^2 - 3 so we have a reflection in the x-axis, and a ...
February 17, 2017

Math
let the length be x let the breadth be y perimeter = 2x + 2y given : length : perimeter = x : 2x+2y = 1:3 x/(2x+2y) = 1/3 3x = 2x+2y x = 2y length : breadth = x : y = 2y:y = 2 : 1
February 17, 2017

Maths
The way you typed it, ?h^2 would simply be h Is that what you want or did you mean: A=?r?(h²-r²) -----> critical brackets I will wait for your reply
February 17, 2017

math
Just noticed that Steve answered the same question 3 years ago, when it was stated as a complete question http://www.jiskha.com/display.cgi?id=1392441787
February 17, 2017

math
So ?
February 17, 2017

math
place 1 on its place on a number line, now count 15 to the right, then 15 to the left I get 16 with1 and -14 with 1 how far from 1 to 16 ? how far from -14 to 1 ?
February 17, 2017

Mathematics
Assuming that "bearing" to you means North = 0 and you are going clockwise. Make a sketch and complete the right-angled triangle: sin20° = y/50 ---> y = 50sin20 = appr 17.1 km or cos70° = y/50 ---> y = 50cos70 = appr 17.1 km
February 17, 2017

Maths
Let's compare the value of $1 at the end of 10 years at both types of interest: compound: Value = 1(1.06)^10 simple: let the rate be r interest = 1(10)(r) = 10r value = 1 + 10r so 1 + 10r = 1.06^10 10r = 1.790847... - 1 r = .0790847... rate = 7.91% to 2 decimals
February 17, 2017

Math
the general term of an AS is a + (n-1)d, where a is the first term, d is the common difference, and n is the number of terms so : a = 0 a+9d = 15 0+9d = 15 d = 15/9 = 5/3 For 10 to be one of the terms a + (n-1)d = 10 0 + (n-1)(5/3) = 10 times 3: 5(n-1) = 30 5n-5 = 30 5n = 35 n...
February 17, 2017

Algebra
(x-1/2)-(x-2/2)+(x-3/2)-...-(x-100/2) = x - 1/2 - x + 2/2 + x - 3/2 - .... - x + 100/2 = x-x+x-x+x-....-x -1/2 + 2/2 - 3/2 - ... + 100/2 looking at the last term, we see there are 100 terms, so the x's drop out = -1/2 + 2/2 - 3/2 - ... + 100/2 = (-1/2)(1 - 2 + 3 - .... + ...
February 17, 2017

3rd Math fraction answer conflict
You are correct at 36/7 another way to look at it: there are 12 half-hours in 6 hours. Have Katie look at a clock. So the length is 12*(6/7) = 36/7 inches
February 16, 2017

Math
In your trig repertoire , you should know the 3 basic trig values of angles 0°, 30°, 45°, 60°, 90° by knowing the ratio of sides of the 30-60-90 and the 45-45-90 degree triangles. This is very very important in any further study of trig. I will do the only...
February 16, 2017

Math
FG----> 25+6.5n, where n is the number of games GB ---> 57 + 2.5n 25 + 6.5n = 57 + 2.5n 6.5n - 2.5n = 57 - 25 carry on
February 16, 2017

Math
hint: sure looks like the coach is collecting $22 from each player. So on Friday, he collects from 2 players, or $ .....? So from p players, he collects $ .... ?
February 16, 2017

Math Help
The order does not matter, so this is a "combination" problem Number of possible 4 cards from the reds = C(26,4) or 26!/(22!4!) number of possible 4 cards from all = C(52,4) or 52!/(48!4!) prob(your event = C(26,4)/C(52,4) = 14950/270725 = 46/833 = appr .055
February 16, 2017

Math (Probability)
Prob(a one) = 1/6 prob(a one) twice = (1/6)(1/6) = (1/6)^2 .. prob(a one) ten times = (1/6)^10 = 1/60466176 = appr .000000016 These are independent events, that is, the die has no memory of what happened before, so each roll is a new event e.g. suppose we flip a coin 3 times. ...
February 16, 2017

Math - Calc/Algebra/Trig
your derivative is ok -4cos^2(x)sin(x)+sin(x) = 0 sinx( -4cos^2 x + 1 ) = 0 sinx = 0 ----> x = 0, ±?, ±2?, ... or 4cos^2 x = 1 cos^2 x = 1/4 cosx = ± 1/2 so x is in any of the 4 quadrants x = ±?/3, ±2?/3 , 4?/3, ±5?/3
February 16, 2017

math
"The sum of the 9th term is 117" makes no sense. Do you mean : the sum of the first 9 terms is 117 or The 9th term is 117 ?
February 16, 2017

Math(Please help!)
You should have an idea what y = 1/x looks like, y = 1/(x+6) simply shifts the y = 1/x six units to the left. the 5 instead of the 1 means that the y value is 5 times as great, so it rises faster or there is a vertical stretch by a factor of 5 e.g. the point (1,1) on y = 1/x ...
February 16, 2017

Math
From your diagram, you should see than tan30° = 20/x, where x is the distance you need. However, a tower 20 cm high ???? You probably meant 20 metres.
February 16, 2017

Math
7. correct 8. area = 29 side = ?29 which is between 5 and 6 since 5^2 = 25 and 6^2= 36 , and your 29 falls between those two
February 16, 2017

Algebra
consecutive odd numbers are 2 apart let the first be x then the 2nd is x+2 and the third is x+4 "the sum of 4 times the largest is -191" makes no sense, "sum" is the result of addition , not multiplication If you meant that the result of 4 times the largest...
February 16, 2017

math
3/4x+5/6x=5x-125/3 the LCD is 12, so multiply each term by 12 9x + 10x = 60x - 500 easy from here.... 2(3x-7)+4(3x+2)=6(5x+9)+3 6x - 14 + 12x + 8 = 30x + 54 + 3 I am sure you an handle it from here
February 16, 2017

Math
For 1. , just replace the x with a+b 2. f(g(x)) = f(2x+5) = -2(2x+5)
February 16, 2017

Math
sum = -1/12 - 4/9 = -19/36 difference = -1/12 - (-4/9) = 13/36 (-19/36) ÷ (13/36 = -19/13
February 15, 2017

Algebra/ please help!!!!
40 hrs a week at $17.00 for 52 weeks = $35,360 Where does the $28,285.28 come from? No idea what the rest of the stuff is supposed to mean.
February 15, 2017

Algebra/ please help!!!!
So much missing information! "WAGE---$ 17.00-an hour---------ANUALLY---28,285.28" --- how many hours a week, how many working weeks in a year? "APARTMENT VALUE 17.34hrs/pay period towards an apartment value of $934/month----ANUALLY---$11,208----TOTAL-------$39,...
February 15, 2017

algebra
6123/x = x + (1/2)x/x times x 6123 = x^2 + (1/2)x times 2 2x^2 + x - 12246 = 0 (x - 78)(2x + 157) = 0 x = 78 or x = -157 check: 6123/78 = 78 + remainder of 39 , which is 1/2 of 78 6123/-157 ? -157 + (????) the divisor is 78
February 15, 2017

Math(Please help!)
Your first step should have been to simplify the expression: (x^2+x-6)/(x^2-9) = (x+3)(x-2)/( (x+3)(x-3) ) = (x-2)/(x-3), x ? 3 take over
February 15, 2017

IB Calculus
since a(t) = 2t - 16 when a(t) = 0 t = 8 v(8) = 64 - 16(8) + 4 = ......
February 15, 2017

Math
Find the volume of the large box Find the volume of the inner box Subtract the two results.
February 15, 2017

Math and Please Help!
nope, look up distributive property in your text or notes and look up examples
February 15, 2017

Calculus
V = (4/3)?r^3 dV/dt = 4? r^2 dr/dt plug in the given stuff 50 = 4?(100)^2 dr/dt dr/dt = 50/(4?(100)^2 ) = .... cm/min
February 15, 2017

math
The first three are rational numbers. For the last one, no idea what the ## in 250## stands for
February 15, 2017

Math
original: Andy ---- a Jack ----- j after first give-away: Andy ---- a/2 Jack ----- j + a/2 after 2nd give-away: Jack --- (2/3)(j + a/2) Andy ---- a/2 + (1/3)(j+a/2) (2/3)(j + a/2) = 20 2(j + a/2) = 60 2j + a = 60 *** a/2 + (1/3)(j+a/2) = 20 times 6 3a + 2(j + a/2) = 120 3a + ...
February 15, 2017

math
The interest in the first year would simply be .1(14,000) = $1,400 The fact of 5 equal payments for 5 years has nothing to do with this. Now for the 2nd year's interest, we need to do further calculations
February 15, 2017

statistics and probability
I agree with it, but I find I would like to meet that .8144 of a person.
February 14, 2017

Math
Hasn't the minute hand completed 1/4 of a rotation? Just look at the face of a clock
February 14, 2017

Math
let f(x) = x^3 + kx - 4 if x-2 is a factor, then f(2) = 0 f(2) = 8 + 2k - 4 = 0 2k = -4 k = -2
February 14, 2017

Grade 6: money and measures
combined rate is 15 litres per minute. amount in 6 min = 6(15) = 90 litres. volume in tank = 2400h cm^3, where h is the height = 2.4h litres, since 1000 c^3 = 1 litre so 2.4h = 90 h = 90/2.4 cm = 37.5 cm <--- the depth of water after both taps ran for 6 minutes b) Does the ...
February 14, 2017

algebra
let the time form 11:00 to the time of overtaking be t hrs distance gone by the truck = 54t distance gone by the van = 64(t-1) but they went the same distance, so ... 54t = 64(t-1) solve for t, and add it to 11:00
February 14, 2017

math
3s + 4j = 360 s + 3j = 220 -----> s = 220 - 3j sub that into the first and solve for j then find s
February 14, 2017

algebra
Plane's speed --- x mph wind speed ----- y mph 2(x-y) = 180 x-y = 90 1(x+y) = 180 x+y = 180 add them: 2x = 270 x = 135 back in x+y= 180 135+y=180 y = 45 state a proper conclusion.
February 13, 2017

Algebra
"and" usually suggests addition, e.g. what is 5 and 6 ? let the number be n "the sum of 4 times a number and 30" --> 4n+30 now twice that ---> 2(4n+30) = 8n + 60
February 13, 2017

Cal 1
S(-3) = 6(-27) + 8(9) + 5 = -85 S(-1) = 6(-1) + 8 + 5 = 7 avg velocity = (7 + 85)/(-1 + 3) = 46
February 13, 2017

Math-Geometry
Good job, you have 1. shown that opposite sides are parallel 2. adjacent sides form a right angle.
February 13, 2017

Math-Geometry
I would first of all plot the points. That would give you an idea which sides would form the rectangle. Since in a rectangle: 1. opposite sides are parallel, you can show this by finding the slopes 2. slopes of adjacent sides are negative reciprocals of each other. Use your ...
February 13, 2017

Math
or number of bags needed --- n amount of peanuts he bought 2n lbs number of bags he needs to buy = 2n/(5/6) = 12n/5 <---- must be a whole number the smallest number of n to make it so, is n = 5 number of bags needed = 5
February 13, 2017

Math
all 3 digit number divisible by 6: 102 108 114 120 126 132 138 144...978 984 990 996 How many of those are there ? (996-102)/6 + 1 = 150 or: An AG with a=102, d = 6, term(n) = 996 term(n) = a+(n-1)d 996 = 102 + 6(n-1) 6n-6 = 894 6n = 900 n = 150 Of those which ARE divisible by...
February 13, 2017

math
so shaded part = 6/20 = 3/10 or 30%
February 13, 2017

math
prob(yellow) = 1/6= x/36, so x = 6 , 6 yellows prob(orange) = 3/4 = y/36, so y = 27, 27 orange remaining 3 must be orange or 1/6 + 3/4 = 11/12 leaving 1/12 for the purple (1/12)(36) = 3 purple
February 13, 2017

Maths
midpoint of (-5,12) and (-1,-12) = ( (-5-1)/2 , (12-12)/2 )) = (-3, 0) I will use vectors to find the points of trisection i.e. in the ratio of 1:2 one point = (1/3)(7,10) + (2/3)(-8,-5) = (7/3, 10/3) + (-16/3 , -10/3) = (-9/3 , 0) = (-3,0) which is the midpoint of above other...
February 13, 2017

Math
In your sketch that you made, you will notice that the diagonals right-bisect each other, creating 4 congruent right-angled triangles. Each of them has angles 30:60:90 degrees the ratio of sides for such a triangle is 1:?3:2 where 2 is the hypotenuse Our hypotenuse is 8 so the...
February 13, 2017

math
I am sure you meant: f(x) = e^x b) f(6) = e^6 f(4) = e^4 avg rate of change from x=4 to x=6 = (e^6 - e^4)/(6-4) = ... , use your calculator
February 13, 2017

Algebra
invested at 2% --- x invested at 3% --- 7000-x .02x + .03(7000-x) = 184 carry on
February 12, 2017

Trigonometry
When you say "a 10 inch wheel" I will assume you have a radius of 10 arc length = rØ, where Ø is in radians 225° = 5?/4 radians 450 = r(5?/4) r = 360/? inches = appr 114.59 inches (big wheel) A point on the smaller wheel has to move 450 inches as ...
February 12, 2017

Algebra
4^4 x 8^8 x 16^16 are all powers of 2 = (2^2)^4 x (2^3)^8 x (2^4)^16 = 2^8 x 2^24 x 2^64 = 2^96 so what do you think?
February 12, 2017

Algebra
looks pretty standard to me. Perhaps you mean: |y|-2=0 |y| = 2 y = 2 or y = -2
February 12, 2017

college algebra
from your data, if h is the height above the water h = -4.9t^2 + 28t + 38 set h = 7 4.9t^2 - 28t - 31 = 0 use the quadratic formula to solve for t, use the positive result
February 12, 2017

college math
At a time of t hours after the action started, - distance remaining for the northbound car before reaching intersection is 3 - 20t - distance remaining for the westbound car before reaching the intersection is 4 - 30t let d be the distance between them d^2= (3-20t)^2 + (4-30t...
February 12, 2017

Algebra (answer check)
y = -x^2 + 2x + 5 the x of the vertex is -b/(2a) = -2/(-2) = 1 plug in x = -1, y = -1+2+5 = 6 vertex is (1,6) -4x^2+7x+5=0 4x^2 - 7x - 5 = 0 x = (7 ± ?129)/8 = appr (7±11)/8 = appr 18/8 or -4/8 or appr 2.5 or -1/2 your choice is good 5x^2 - 20 = 15x x^2 - 3x - 4...
February 12, 2017

Math; Calculus
from the given data: h = -16t^2 + 55t + 6 this is a parabola, we need its vertex. the t of the vertex is -b/(2a) = -55/-32 = 55/32 seconds plug that into equation to find max height it is in the air for h > 0 let's see when h = 0 0 = -16t^2 + 55t + 6 16t^2 - 55t - 6 = 0...
February 12, 2017

Algebra
speed of current --- y speed of swimming ---- x x+y = 5 x-y = 2 solve, I suggest adding them, etc
February 12, 2017

Algebra
amount of cashews --- x lbs amount of raisins ---- 4.5 - x lbs 2.5x + 1.25(4.5-x) = 2(4.5)
February 12, 2017

math
let the second be x ft long then the first is x+4.25 the third is x+2.24 x + x+4.25 + x+2.24 = 10 carry on
February 12, 2017

math
cost price = 525 18 eggs = 1.5 dozen selling price = 23.5(26) = ... profit or loss = selling price - 525 = .... percent profit = ....
February 12, 2017

math
collins meant: (a+b+c)/2 = s
February 12, 2017

number base help plz
Steve is simply using the definition of a number with a different base. Just like 57810 = 5(10^2) + 7(10^1) + 8(10^0) 1234 = 1(4^2) + 2(4) + 3 = 16 + 8 + 3 = 24 + 3 ---> Steve noticed the multiples of 8 = 3(8) + 3 = 338
February 12, 2017

Math
Say what ?
February 11, 2017

algebra
your function is a straight line - from your equation we can tell that the slope is -2 and the line passes through (-8,7) All you need is another point and you can draw it. Why not pick something nice like x = 0 So we get: y-7 = -2(8) y = -16+7 = -9 take over
February 11, 2017

Calculus
A rough sketch of the two functions y = x , and y = 1+sinx will show that y = x clearly crosses y = 1 + sinx only once. So your statement is not correct. evidence: http://www.wolframalpha.com/input/?i=solve+x%3D1%2Bsin(x)
February 11, 2017

Algebra
x/3 + 5 = 3x/2 times 6. 2x + 30 = 9x 7x = 30 x = 30/7 check: (1/3)(30/7) + 5 = 45/7 3/2(30/7) = 45/7 my answer is correct
February 11, 2017

math
They do not intersect at (3,4) (3,4) does not satisfy g(x) = 2^x - 1 RS = 2^3 - 1 = 7 LS = 4, no good (3,4) work in f(x) = -5/3x + 9 RS = -5/3(3) + 9 = 4 So it does work in the other equation. did you mean g(x) = 2^(x-1) ?? RS = 2^2 = 4 = RS you must have meant that! so ...
February 11, 2017

math
Did you make a sketch?? The difference in their connection points is 4 m. and you have a triangle with base 10, height 4 and missing hypotenuse x^2 = 4^2 + 10^2 carry on
February 11, 2017

Math
Maria "guessed" correctly, I got the same answer. So none of the answers supplied are correct. Either typo or misprint.
February 11, 2017

Matj
I will assume the difference to be between pairs of coupons possible cases: 5,1 6,1 6,2 7,1 7,2 7,3 8,1 8,2 8,3 8,4 9,1 9,2 9,3 9,4 9,5 10,1 10,2 10,3 10,4 10,5 10,6 total 21 number of pairs = C(10,2) = 45 prob(of your event) = 21/45 = 7/15
February 11, 2017

math
Hint: The diagonals of a rhombus right-bisect each other. Another hint: Make a sketch. What type of triangles do you see? Do you know the legs of those triangles?
February 11, 2017

Math
What is the LCM of 2, 6, and 9 ?
February 11, 2017

algebra
time spent cyling --- x hrs times spent running --- (2.5 - x) hrs 10x + 6(2.5-x) = 21 carry on
February 11, 2017

math
Scott is absolutely right, if you had taken the 10 seconds to complete his calculations.
February 11, 2017

n
Let's use a sine curve, we could use a cosine as well amplitude is 10, so h = 10sin kt the period is 6 minutes, so 2?/k = 6 ----> k = ?/3 sofar: h = 10sin (?/3 t) this has a min of -10, but our min is to be +1, so we have to raise everything up by 11 so far: h = 10sin...
February 10, 2017

Math
Number of Yen remaining = 110682 - 87438.78 = 23243.22 $1100US = 110682 Yen 1 Yen = 1100/110682 = $.009938382 so 23243.22 Yen = .009938382(23243.22) = $231 or 1100/110682 = x/23243.22 x = 231
February 10, 2017

math
correct, only a = 0 if x = 0 then in x/y=2 0/y = 2, which cannot be, so x ? 0 if y = 0, we would be dividing by zero to get 2, which is rather silly, so y ? 0 if a = 0, x/y =2 has nothing to do with it, but x*y*0 = 0, which is true
February 10, 2017

math
size of original piece of material: x cm by x cm after cut-out base is (x-8) by (x-8) height = x V = x(x-8)^2 = 576 x^3 - 16x^2 + 64x - 576 = 0 Nasty equation to solve. Have you learned any methods to solve a cubic? Newton's Method is probably the best way, but you have to...
February 10, 2017

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