Friday
April 29, 2016

Posts by Reiny

Total # Posts: 34,383

Maths
In my diagram, I have the perpendicular from T go PC meeting PC at S, giving me 2 right angled triangles. In triangle CST: tan30° = 6/CS CS = 6/tan30 in triangle PST: tan40° = 6/SP SP = 6/tan40 PC = CS+SP = .... you do the button-pushing
March 3, 2016

Finance
I am not familiar with US mortgage laws. What is this "3.5% closing cost" ? so is the original mortgage: add 3.5% to 225,000, then take 90% of that? That would be 225,000(1.035)(.9) = $209,587.50 confirm that before I proceed
March 3, 2016

Math
(-1,14), (0,10), (1,8), (2,?), (3,10), (4,?) and (5,20) the missing values should be like: (-1,14), (0,10), (1,8), (2,8), (3,10), (4,14?) and (5,20) Now if you put those same x value into the straight line you get: (-1,6), (0,7), (1,8), (2,9), (3,10), (4,11), and (5,12) Notice...
March 3, 2016

math
Join A and B to O, the centre of the circle So we have triangle ABO with all 3 sides known. We can use the cosine law to find angle Ø 6^2 = 9^2+9^2-2(9)(9)cosO 162cosØ = 126 cosØ = 126/162 = 7/9 Ø = 38.94...° (I stored it in calculator's ...
March 3, 2016

Algebra
amount = 6300(1.06)^3 = 7503.40 how did you get your answer ??
March 2, 2016

trigonometry (Course and Bearing)
According to my sketch: tan46°10' = 7/AP AP = 7/ tan46°10' = .... sin46°10' = 7/BP BP = 7/sin46°10' = ....
March 2, 2016

Trig
Of course I can't see where your Ø is let's assume it is opposite the smallest side. 10^2 = 17^2 + 20^2 - 2(17)(20)cosØ 680cosØ = 589 cosØ = 589/680 Ø = appr 29.98° If otherwise, make the necessary changes
March 2, 2016

Math
1/2 ÷ 1/8 =
March 2, 2016

Math
be more specific please
March 2, 2016

Algebra
ummh, notice that two of the terms has a single decimal place with that decimal being an even number What happens when you multiply any even number by 5 ?
March 2, 2016

finance
PV = 3000(.96) + 3000(.96)^2 or PV = 3000(1/04)^-1 + 3000(1.04)^-2 depending on how "annual discount rate" is defined in your course. btw, they yield different results.
March 2, 2016

Algebra
pop(chessville) = 50,000(1.07)^n pop(checkerville) = 70,000(.96)^n we want to know when 50,000(1.07)^n ≥ 70,000(.96)^n divide by 10,000 5(1.07)^n = 7(.96)^n take logs of both sides and use rules of logs log5 + nlog1.07 = log7 + nlog.96 nlog1.07 - nlog.96 = log7 - log5 n(...
March 2, 2016

precalculus
Make a reasonable sketch. Using vectors and using R to be the resultant vector: R = (180cos300,180sin300) + (50cos245,50sin245) = (90,-90√3) + (-21.1309.. , -45.31538..) = (68.869.., -201.1996...) Magnitude = √(68.869^2 + (-201.1996..)^2) = appr 212.66 km direction...
March 2, 2016

MATH.
done yesterday http://www.jiskha.com/display.cgi?id=1456884647
March 2, 2016

math
6x^3 + 3x^2 - 9x what about it ?
March 1, 2016

Math
so number = a e^(kt) 10,000 = a e^(3k) 40,000 = a e^(5k) divide the 2nd by the 1st: 4 = e^(2k) 2k = ln4 k = (ln4)/2 so N = a e^( (ln4)/2 t) so we need a a e^(3ln4/2) = 10,000 a = 10,000/8 = 1250 initial count is 1250 bacteria
March 1, 2016

math
what is 6000(1.02)^28 ?
March 1, 2016

Math
time the dog wants to go outside in that time frame = (7/12)(60) = 35 minutes so not wanting to outside = 25 minutes percentage of time not going out = 25/60 = appr 42%
March 1, 2016

Math
prob = 6/10 = 3/5 a cube has 6 sides, so division by 6 would be the model for probs, we need a division by 5 or 10 or 15 ,etc
March 1, 2016

Pre-Calc
did you test the answer in the first equation? It clearly works in the last two equations.
March 1, 2016

Algebra
speed of second train ---- x mph speed of first train --- 2x-10 mph When they meet they would have traveled the same time let that time be t hrs distance gone by first train = tx distance gone by 2nd train = t(2x-1) tx + t(2x-1) = 220 tx + 2tx - t = 220 t(3x-1)=220 t = 220/(3x...
March 1, 2016

Calculus
I have seen this question, where we have to find the other sides so that the perimeter is a minimum, but ... The way it is worded... there is an infinite number of possible lengths. e.g if the side along the x-axis is 5, then the equation of the line passing through (1,1) has ...
March 1, 2016

math
f∘g(x)= f(g(x)) = f(4-x^2) = 4(4-x^2) - 3 simplify do the 2nd one in the same way
March 1, 2016

Math
Did you mean f(x) = √(x+1) ?? I will assume that. f∘g = f(g(x)) = f(3x-5) = √((3x-5) - 5) = √(3x - 10) domain: 3x-10≥0 3x≥10 x ≥ 10/3 ( I will let you switch this to "interval notation, I like the "old way" better) g&#...
March 1, 2016

algebra
first condition: XX2 XX3 XX5 XX7 Second condition: hundreds is twice tens 842 632 422 212 843 .... ... 847................217 There will be 16 of those I will leave it up to you to decide how many of those are prime numbers. (remember, just because a number ends in an odd ...
March 1, 2016

math
Just a simple case of tan38 = h/6.6 h = 6.6tan38° = ....
March 1, 2016

math
amount of 30% solution --- x gal amount of 14% stuff ------ 60-x solve for x .30x + .14(60-x) = .20(60) or if you want two variables: x+y = 60 .30x + .14y = .20(60)
March 1, 2016

math plz help i cant understand this. :'(
Did you plot the points? Look like a trapezoid. AB is a horizontal line, so that AB = 6 AC and BC are parallel So area = (1/2(AC + BC)(AB) = (1/2)(4+6)(6) = 30 square units
March 1, 2016

math :D
Easiest to check would be the median We have an even number of data values, so the median is the average of the two middle numbers. so (23+25)/2 = 24, that rules out #1 and #2 the mode is clearly 25 so we have to find the mean: add them up and divide by 8 to see what you get
March 1, 2016

@ Mary - Calculus
Mary, what part of yesterdays solution did you not like ? http://www.jiskha.com/display.cgi?id=1456770767 Always check to see if your question has been answered before reposting the same thing. That way we avoid unnecessary duplication of work.
March 1, 2016

mathematics
so 75% would be 45 .75x = 45 x = 45/.75 = ...
March 1, 2016

math
distance = 4.9t^2, when t=1 distance = 4.9 m
March 1, 2016

math
This webpage is perfectly suited for your type of problem http://davidmlane.com/hyperstat/z_table.html Just enter the data
February 29, 2016

Calculus
I would assume you are using the cosine law. let the distance between the two tips be x x^2 = 4 + 9 -2(2)(3)cosØ x^2 = 13 - 12cosØ 2x dx/dt = 12sinØ dØ/dt given: dØ/dt = .5 , Ø = π/4 for Ø = π/4 x^2 = 13 - 12cosπ/...
February 29, 2016

Math
equation of tangent: y - 5/3 = (-5/9)(x - 5) y = (-5/9)x + 25/9 + 5/3 y = (-5/9)x + 40/9 check my arithmetic
February 29, 2016

math
Did you make a sketch? On mine I let the top of the tree be A and its bottom be B look at triangle APB. angle ABP = 120° , AP = 4√3, BP = 4 by the sine law: sinA/4 = sin120/4√3 sinA = 4(√3/2)/(4√3) = .5 A = 30° so angle APB = 180-120-30 = 30°
February 29, 2016

math
Make a little diagram of what actually happens. After the first bounce, the ball goes up and down 2/3 of it previous bounce, but the first event can be considered only half a bounce. so I am going to consider this to be a geometric series, pretending the first bounce is ...
February 29, 2016

math
I see 2 similar triangles. let length of Christa's shadow be x ft let length of Glad's shadow be y ft so 5/x = 6/y 6x = 5y we also know x+y = 15 or y = 15-x sub into the first: 6x = 5(15-x) 6x = 75-5x 11x = 75 x = 75/11 ft = appr 6.82 ft y = 15-75/11 = 90/11 ft = appr ...
February 29, 2016

math
just use the formula PV = 1000(1.05)^-8 = ...
February 29, 2016

math
I will assume this is "simple interest" let the rate be r, let the principal be p so (15/12)(rp) = 455 rp = 364 for only 10 months interest = (10/12)(rp) refund = 455 - (10/12)(rp) = 455 - (5/6)(364) = $151.67
February 28, 2016

geometry
Ladder is 12 feet out and 16 ft up, A VERY UNSAFE WAY TO PUT THE LADDER!! length of ladder --- L L^2 = 12^2+16^2 = 400 L= √400 = 20 new position: base = 14 , height = ? , L = 20 solve: h^2 + 14^2 = 20^2
February 28, 2016

math
Good grief, haven't seen that type of question in about 50 years. didn't know they still used it . I will describe the method and then attempt to explain what happened. They are using the word "normal" to mean perpendicular. e.g. in your equation, 2x+3y - 5...
February 28, 2016

math
sinx < -√3/2 consider sinx = -√3/2 by the CAST rule and knowing that sin 30° = +√3/2 x = 210° or x = 330° also, you should know the general shape of the sine curve. from the above the curve would be below -√3/2 between 210° and 330&...
February 28, 2016

Geometry
recall that sin^2 Ø + cos^2 Ø = 1 so sin^2 Ø + 9/64= 1 sin^2Ø = 55/64 sinØ = √55/8 then cscØ = 8/√55 or 8√55/55
February 28, 2016

Pre-Calculus
Important info at the end: "with equal amounts invested in short- and intermediate-term bonds. " So let each of those amounts be x then the amount invested at long-term be 100,000 - 2x He wants to end up with a 5.1% profit on the total 100,000 or $5100 Now it is easy...
February 28, 2016

Algebra
I will assume you made a diagram. On my diagram, I have each of the long sides as y, and each of the 3 shorter sides as x so we have 3x + 2y = 440 y = (440 - 3x)/2 = 220 - (3/2)x area = xy = x(220 - (3/2)x) = 220x - (3/2)x^2 from the subject title, I assume you don't take ...
February 28, 2016

math
those solutions where 0 ≤ x ≤ 2π 2cos^2x-5cosx+2=0 this is a standard quadratic where your variable is cosx How about doing this ? let t = cosx then we have 2t^2 - 5t + 2 = 0 , which factors to (2t - 1)(t - 2) = 0 t = 1/2 or t = 2 so cosx = 1/2 or cosx = 2 ...
February 28, 2016

maths
I can't see any other way than listing the possible cases and finding the total score for each case. Using the first letter of each outcome, we could have BBBB -- 36 BBBS -- 34 BBBT -- 31 BBBO -- 28 BBSS -- 32 BBTT -- 26 BBOO -- 20 BBST -- 29 BBSO -- BBTO etc, watch for ...
February 28, 2016

math
hard to get the spacing correct, I will use ** for spacing 3|2**0**-1**0***7****1 ******6**18**51*153*480 ***2**6**17**51*160*481 f(3) = 481
February 28, 2016

Math
prob(hit) = .42 prob(no hit ) = 1 - .42 = .58 at least 2 hits out of 4 ---> exclude : no hits, 1 hit prob(no hits) = C(4,0)(.42)^0 (.58)^4 = .113165 prob(1hit) = C(4,1)(.42)(.58)^3 = .32779 prob(at least 2 hits) = 1 - (.113165 + .32779) = appr .559 or you could do prob(...
February 28, 2016

math
Tell me what you got, then we'll both be happy
February 28, 2016

math
This is almost the same kind of question that I answered for you here : http://www.jiskha.com/display.cgi?id=1456693077 Did you look at it, and learn from it? I will give you one hint for this one: cos (2Ø) = cos^2 Ø - sin^2 Ø let me know how you made out.
February 28, 2016

math
remember cos^2 Ø + sin^2 Ø = 1 .36 + sin^2 Ø = 1 sin^2 Ø = .64 sinØ = .8 sin 2Ø = 2sinØcosØ = 2(.8)(.6) = .96 2Ø = sin^-1 (.96) or arcsin(.96)
February 28, 2016

Geometry/Algebra
welcome!
February 28, 2016

Geometry/Algebra
Make a sketch of a right-angled triangle ABC with angleB = 90° Draw in the altitude from C to hypotenuse AC to meet it at D. You now have 3 similar right-angled triangles. (easy to see by considering the angles) I will list them, with corresponding vertices in the same ...
February 28, 2016

Math
Why could you not check them?? is (1/8)% of 32 = .04 ?? (1/800)(32 = 32/800 = .04 , so YES x(1.8) = 3 x = 3/1.8 = 1.6666.. or 166.66..% or 166 2/3% check that: take 166.66..% of 1.8 = (166.666../100 )(1.8) = 3
February 28, 2016

math
a+d = 50 a + 4d=65 subtract them 3d = 15 d = 5 then a+5=50 a=45 term40 = a + 39d = 45 + 39(5) = 240
February 28, 2016

futher maths
What are we doing to it ? is it (√3 - √2)/2 or √3 - (√2/2) ?
February 28, 2016

Math 12
You should have available to you : - either in your notebook -or in your text - or memorized , the ratio of sides for the 30-60-90 as well as the 45-45-90 right-angled triangles you should also have memorized the simple conversion from degrees to radians of the following 30&...
February 28, 2016

Math
done, look further up to your other post
February 28, 2016

Finance
Value at the end of 6 years = 1120 + 1120(1.12) + 1020(1.12)^2 + 1020(1.12)^3 + 920(1.12)^4 + 920(1.12)^5 = 8155.91 now the rate goes down to 7% for the next 59 years. Final value at age 65 = 8155.91(1.07)^59 = 441,687.52 but they only paid out $430,000 while using that money ...
February 28, 2016

business math
exactly 3 men ---> need 2 women number of choices = C(7,3) x C(5,2) = 35 x 10 = 350 more women than men ---> 5 women, 4W-1M, 3W-2M = C(5,5) + C(5,4)xC(7,1) + C(5,3)xC(7,2) = 1 + 35 + 10(21) = 246
February 28, 2016

math
so he biked 1 mile at 12 mph and the other 1 mile at x mph 1/12 + 1/x = 1/4 ---> 15 min = 1/4 hr times 12x, (don't like fractions) x + 12 = 3x x = 6 so his speed for the second part was 6 mph check: time at 12 mph = 1/12 hr = 5 minute time at 6 mph = 1/6 hr = 10 min for...
February 28, 2016

Math
for the AS x-6 = y-x 2x-y = 6 or y = 2x-6 for the GS y/x = 16/y y^2 = 16x sub in the 1st (2x-6)^2 = 16x 4x^2 - 24x + 36 = 16x 4x^2 -40x + 36 = 0 x^2 - 10x + 9 = 0 (x-1)(x-9) = 0 x = 1 or x = 9 if x = 1, y = -4 if x = 9 , y = 12 check: 1st case: 6, 1, -4, 16 , the first 3 are ...
February 28, 2016

math
yes recall that (a/b)^n = a^n/b^n so (1/a)^-n = 1^-n / a^-n but (1)^anything = 1 = 1/a^-n
February 28, 2016

math
for the first one: (-1)^(2n) = +1 2n is an even number, so when you multiply -1 an even number of times you get a positive e.g. (-1)^12= ( (-1)^2 )^6 = 1^6 = 1 but (-1)^13 = (-1)^12 (-1) = (+1)(-1) = -1 so if you raise (-1)^odd, you get -1 which answers the second part since ...
February 28, 2016

FINANCE
PV of loan = .75(3250000) = $2,437,500 paym = 15800 n = 12(35) =420 let the monthly rate be i 2437500 = 15800( 1 - (1+i)^-420)/i 154.2721519 i = 1 - (1+i)^-420 This is a very nasty equation to solve. Back in the "good ol' days", we used a method called ...
February 28, 2016

Finance
If she has 2500,000 and she gets 12.5% per year in interest, she would earn $312,500 per year right now. Heck!, she should retire right now but according to your question 2.5 million(1.125)^n = 7.5 million 1.125)^n = 3 n log 1.123 = log3 n = appr 9.3 years
February 27, 2016

precal
It said diameter = 22, so radius is 11 I used 2πr = 2(11)π = 22π
February 27, 2016

precal
circumference = 2π(11) = 22π inches so in 1 minute a point on the rim covers 31(22π) or appr 2142.566 inches since linear velocity = distance/time ....... your turn.
February 27, 2016

math
sinØ = y/r = 1/9 ---> y = 1, r = 9 Make a sketch of the triangle in quad II so x^2 + y^2 = 9^2 x^2 + 1 = 81 x^2 = 80 x = ±√80 = ±4√5 but we are in II, so x = -4√5 sinØ = 1/9 ---> the given cosØ = -4√5/9 tan&...
February 27, 2016

Mathematics
you have to use the product rule, with your notation, it would be d(uv) = uv' + vu' = (-8sin(2x))(cos(3x)) + (4cos(2x)(-3sin(3x) ) = -8sin(2x)cos(3x) - 4sin(3x)cos(2x)
February 27, 2016

math
To make 10 L in total you will need x L of the 18% solution and 10-x L of water. .18x + 0(10-x) = .12(10) .18x = 1.2 x = 1.2/.18 = 120/18 = 20/3 He needs 20/3 L or 6 2/3 L of water. (btw, a Russian would never dilute his alcohol)
February 27, 2016

Calculus Pre Test Questions Monday Part 4
your symbols came out strange. Is 3􏰄<t􏰄<3.01 supposed to say 3 ≤ t ≤ 3.01 ?
February 27, 2016

Calculus
So you have a split function f(x) = 4-x^2 for x<1 f(x) = 2x+1 for x > 1 (you don't say what happens at x = 1 ) first slope = -2x, second slope is a constant 2 a) (-1,3), since x<1, slope = -2(-1) = 2 b) (2,5), since x > 1, slope = 2
February 27, 2016

Calculus
2a) I will assume you mean f(x) = 3/(x+1) I would write it f(x) = 3(x+1)^-1 then f ' (x) = -3(x+1)^-2 = -3/(x+1)^2 at P(2,1), slope = -3/(3)^2 = -3/9 = -1/3 h(x) = 2/√(x+5) = 2(x+5)^(-1/2) h ' (x) = -1(x+5)^(-3/2) = -1/( √(x+5) )^3 you finish it
February 27, 2016

Algebra
number of fifties --- x number of tens ---- x+14 number of twenties -- 2x+4 50x + 10(x+14) + 20(2x+4) = 1720 Solve for x, and all shall be revealed.
February 27, 2016

math
Use the discriminant property if we have real roots, then b^2 - 4ac > 0 px^2-p+10=2(p+2)x px^2 - p + 10 = 2px + 4x px^2 - 2px - 4x + 10 = 0 px^2 + x(-2p-4) + 10 = 0 b^2 - 4ac > 0 (-2p-4)^2 - 4(p)(10) > 0 4p^2 + 16p + 16 - 40p > 0 4p^2 - 24p + 16 > 0 p^2 - 6p + 4...
February 27, 2016

math
for 2 equal roots, b^2 - 4ac = 0 9p^2 - 4(p)(p+q) = 0 9p^2 - 4p^2 - 4pq = 0 5p^2 - 4pq = 0 p(5p - 4q) = 0 p = 0 or p = 4q/5 but p≠0 or else we don't have a quadratic, so p = (4/5)q
February 27, 2016

math
You must be talking about the simple interest formua I = PRT 700 = 3500(r)(4) r = 700/(14000) = ...
February 27, 2016

Geometry
"One Secant has 4 and x" is not clear. Is 4 the length of the entire secant or just the part inside the circle? In general, if you have two secants to the same circle (whole of secant #1)(outside part of secant#1) = (whole of secant#2)(outside part of secant#2) So ...
February 27, 2016

Algebra 2
y = -.23x + 56.78 or y = (-1/2)x + 3
February 27, 2016

math
speed of private jet --- x mph speed of commercial jet --- 2x-143 mph They both went the same distance, so ... 4(2x - 143) = 6x solve for x
February 27, 2016

algebra
f(x)-g(x) = 9x^3+2x^2-5x+4 -(5x^3-7x+4) = 9x^3+2x^2-5x+4 -5x^3+7x-4 = 4x^2 + 2x^2 + 2x looks like you are correct
February 27, 2016

Alg2
Why make things complicated ? Just solve it .... (1/4)x-3=(1/2)x+8 times 4, the LCD x - 12 = 2x + 32 -x = 44 x = -44 Where does y come from in the pairs of equations?
February 27, 2016

calculus
I see 4 questions posted in quick succession. You have given no indication of any start to these on your part, nor have you told us where your problems are. This looks like an assignment or homework. Surely you realize that if just do these questions for you, you will not ...
February 27, 2016

Math
let the number of boys be 5x and the number of girls be 6x 5x+6x=44 11x=44 x=4 so we have 20 boys and 24 girls (notice 20:24 = 5:6)
February 27, 2016

financial maths
i = weekly rate = .0665/52 = .001278846 n = number of payments = 52(15) = 780 Amount repaid = present value of loan = 200( 1 - 1.001278846^-780)/.001278846 = appr $98,677.00
February 27, 2016

math
Alice --- x Peter --- x+5 John ---- 2x+10 5 years from now: John -- 2x+15 Alice -- x+5 2x+15 = 3(x+5) -x = 0 x = 0 This question is bogus, even though the answer meets the original conditions. Unless Alice was just born, it makes little sense i.e. Alice -- 0 years Peter --5 ...
February 27, 2016

math
let the 3 numbers be x, x+1, and x+2 3x = x+1 + x+2 3x = 2x+3 x = 3 Finish it up, and check my answer to see if it meets the given conditions
February 27, 2016

math
what is 4x3 ?
February 27, 2016

algebra or algebra1
Not sure of your unusual notation. did you mean |x-6| is multiplied by 7 ? Ok, then ... f(-1) = |-1-6|7 - (-1) = 49+1 = 50
February 27, 2016

Math Word Problem
same type of problem as your previous post .... students --- x adults ----- y x+y = 110 ---> y = 110-x 13.5x + 16.5y = 1581 sub the first into the second: 13.5x + 16.5(110-x) = 1581 13.5 + 1815 - 16.5x = 1581 -3x = -234 x = 78 So 78 students and 32 adults
February 27, 2016

Math Word Problem
Look at the response to this question last night by both Steve and I. All you have to do is change the original second equation, and solve. http://www.jiskha.com/display.cgi?id=1456542484
February 27, 2016

Maths
You have your thinking backwards. an example of the above would be both 12 and 30 are divisible by 3 then their difference is divisible by 3 check: difference = 30-12 = 18 is 18 divisible by 3 ? YES actual proof: let the two numbers be kx and ky. kx and ky are both divisible ...
February 26, 2016

Algebra
What does your text or your notes say about y = mx + b ?
February 26, 2016

Math
using the definitions: a+2d + a+8d = 20 2a + 10d = 20 a + 5d = 10 ** a+11d - (a+3d) = 32 a+11d - a - 3d = 32 8d = 32 d = 4 sub into ** a + 20 = 10 a = -10 state your conclusion.
February 26, 2016

Math Word Problem
number of 4-credit courses --- x number of 5-credit courses --- y x+y = 52 4x + 5y = 22 This has no positive x and y solutions. Check your question or your typing How can a total of 52 courses yield only 22 credits, unless they failed most of the courses ???? Even if courses ...
February 26, 2016

math
You don't say what kind of a prism. I will assume it is a rectangular prism, (fancy word for box) each cube has a volume of (1/2)^3 or 1/8 inches^3 number that will fit the box = 56/(1/8) = 448 cubes e.g. the box could have been 4 in by 7 in by 2 in for a volume of 56 ...
February 26, 2016

Pre calculus
Do you really think that somebody will give their free time and help you after such a rude and disrespectful response to one of our valuable and trusted tutors ? I certainly don't feel such an inclination.
February 26, 2016

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