Sunday
September 21, 2014

Posts by Reiny


Total # Posts: 27,130

Algebra 1--Please, help me!
1. for the x-intercept let y = 0 ---> x = 2/3 for the y-intercept , let x = 0 ---> y = -2 2. (3m^2 n)/(5m)(20mn/n^6) = (3mn/5)(20m/n^5) = 12m^2/n^4 ------> a) 3. 3/x + 3/(5x) LCD = 5x = 15/(5x( + 3/(5x) = 18/(5x)-----> c)
June 9, 2014

Algebra
domain: { -7,9,0} range : { 5,-4,3,-7}
June 9, 2014

Algebra 1--Please, check my answer!
1. the slope of x+2y = -6 is -1/2 so we are looking for a line with slope +2 so anything starting with 2x-y = .... or -2x + y = ... will do. looks like b) to me 2. They all factor and simplify a) 3(x+2)/((x+2)(x-1)) = 3/(x-1) , x ≠ -2 b) 3(x-1)/((x-1)(x-1)) = 3/(x-1) , x...
June 9, 2014

algebra/can you show me how to solve problem
f(x) = x^2 + 2 f(-3) = (-3)^2 + 2 = 9+2 = 11 notice that I substituted x with the given value of x wherever I saw an x do the others the same way
June 9, 2014

Algebra 1--Please, help me!
see later post
June 9, 2014

Algebracan you answer my question
http://www.wolframalpha.com/input/?i=plot+x-y%3D4+%2C+2x%2B3y%3D13+
June 9, 2014

Math
let y = -x^2 + 5x + 5 dy/dx = -2x + 5 = 0 for a max of y 2x = 5 x = 5/2 when x = 5/2 y = -25/4 + 5(5/2) + 5 = 45/4 you should recognize y = -x^2 + 5x + 5 as a downward opening parabola , the max is 45/4 when x = 5/2
June 9, 2014

Calculus
if f ' (x) = 2x- 3x^2 f(x) = x^2 - x^3 + c f(0) = 0-0+c f(3) = 9 + 27 + c = 36+c change from f(0) to f(3) = 36+c - c = 36
June 9, 2014

algebra
Your expansion is incorrect 3(x-5)(x+5) = 3(x^2 - 25) = 3x^2 - 75 Since you wanted a quadratic equation, it should be 3x^2 - 75 = 0
June 9, 2014

algebra
What did you get ?
June 9, 2014

Algebra
follow the same steps that I showed you in your previous post of the identical type of question. It appears you never even looked at it.
June 9, 2014

Algebra
that would simply be f(x) = 2(x+3)(x+4) = 2x^2 + 14x + 24
June 9, 2014

Math
1by1 --- 64 of them 2by2 --- 49 3by3 --- 36 4by4 --- 25 5by5 --- 16 6by ----- 9 7by7 ---- 4 8by8 ---- 1 total = 204 There can only be an equal number of reds and blacks in the even-numbered squares, so 64 + 36 + 16 + 4 + 1 = 121 121 blocks have the same number of reds and ...
June 9, 2014

Probability!
since you are replacing the marble, the second draw is not affected by anything you did before. so Prob(red, then blue) = (8/43)(12/43) = 96/1849
June 9, 2014

MATH
correct
June 9, 2014

MATH
For the first, the following are divisible by 3: 3 6 9 so what do you think?
June 9, 2014

math.
0 < (x+3)/2 < 5 multiply by 2 0 < x + 3 < 10 subtract 3 -3 < x < 7
June 9, 2014

Algebra
I think the main purpose of the question, even though they did not say that, was to show that the midpoint of the hypotenuse is equidistant from the 3 vertices. All I did with the slope calculation was to show that the triangle is indeed right-angled. Other than that, finding ...
June 9, 2014

Algebra
I don't understand your question. I DID use the distance between two points formula, I just did not show the subtraction since that is easily done in your head. here is one of them with all steps : AM = √( 2.5 - 1)^2 + (3.5-1)^2 ) = √( 1.5^2 + 2.5^2) = √2...
June 9, 2014

Algebra
Your diagram should show that you have a right angle at B , but let's prove it anyway. slope AB = (2-1)/(5-1) = 1/4 slope of BC = (6-2)/(4-5) = -4 YES, AB is perpendicular to BC, thus AC is a hypotenuse midpoint of AC = M( (1+4)/2 , (1+6)/2) = M(5/2 , 7/2) = M(2.5 , 3/5) ...
June 9, 2014

Algebra
(f*g)(x) = (2x+5)(x^2 - 3) = 2x^3 + 5x^2 - 6x - 15 do the other one in the same way
June 9, 2014

trig
let's fit the data to a curve of the type f(t) = a cos k(t +d) + c from highest to lowest = 65-25= 40 cm so a = 20 from highest to lowest = .3 s to 1.8 s so period = 3 seconds 2π/k = 3 k = 2π/3 so far we have f(t) = 20 cos (2π/3) (t +d) + c let's raise ...
June 9, 2014

Maths, Divine International Public School
cotA = 8/15 tanA = 15/8 so y=15, x=8 r^2 = 15^2 + 8^2 r = √289 = 17 sinA = 15/17 cosA = 8/17 then (1+SinA)(1-SinA)/(1+CosA)(1-CosA) = (1 - sin^2 A)/(1 - cos^2 A) = (1 - 225/289)/(1 - 64/289) = (64/289) / (225/289) = 64/225
June 8, 2014

Math
upwards: f(x) = (x+2)(2x+5) downwards f(x) = -(x+2)(2x+5) expand if needed
June 8, 2014

Math 11
I hope you made a diagram. label the window position P label the top of the statue T label the bottom of the statue B So we want TB I can find BP sin34° = 20/BP BP = 20/sin34 let's use the sine law in triangle TBP TB/sin4 = BP/sin120 TB = BPsin4/sin120 = (20/sin34)(...
June 8, 2014

Math helpppp!
You gave the equation in vertex form so the vertex is easily read to be (6,3) for standard form, just expand your function h(x) = x^2 -12x + 36 + 3 = x^2 - 12x + 39
June 8, 2014

math
Euler said: V + F - E = 2 so if 4 + 6 - E = 2 -E = -8 E = 8 It has 8 edges
June 8, 2014

math
This is the same as finding a Lowest Common Denominator 20 = 2*2*5 24 = 2*2*2*3 30 = 2*3*5 so we need: 2*2*2*3*5 or 120
June 8, 2014

math
let a^(2/3) = y for easier typing then x = y - 1/y = (y^2 - 1)/y x^3 = (y^6 -3y^4 + 3y^2 - 1) / y^3 = (a^4 - 3a^(8/3) + 3a^(4/3) - 1)/a^2 or a^2 - 3a^(2/3) + 3a^(-2/3) - a^-2 3x = 3a^(2/3) - 3a^(-2/3)
June 8, 2014

math
present age: michael ---- x max ------- x-5 4 years ago: michael ---- x-4 max ------- x - 9 x-4 + x-9 = 25 2x = 38 x = 19 Michael is now 19 , and Max is now 14 check: 4 years ago , Michael was 15 and Max was 10 was the sum of their ages at that time 25? YES
June 8, 2014

Math
The equation for your cost: cost = .1(m-500) + 25 , where m is in minutes so : .1(m-500) + 25 > 30 For the second part, m = 525 cost = .1(525-500) + 25 = $27.50
June 8, 2014

Pre-Calc
For any (r,Ø) x = rcosØ, y = rsinØ so x = 5cos(π/4) , y = 5sin(π/4) x = 5√2/2 , y = 5√2/2 so you have the point (5√2/2 , 5√2/2) (I don't see why you would want to write that in decimals, since you have to round it) ...
June 7, 2014

Algebra confused/Thank you
You should be able to read the solution. http://www.wolframalpha.com/input/?i=plot+3x+%2B+2y+%3D+5+%2C+4x+−+3y+%3D+1
June 7, 2014

maths
a+bi = √(1+i)/√(1-i) = √(1+i)/√(1-i) * √(1-i)/√(1-i) = √(1 - i^2) / (1-i) = √(1 - i^2) / (1-i) * (1+i)/(1+i) = √2(1+i)/2 = √2/2 + √2/2 i so a = √2/2 and b=√2/2 and a^2 + b^2 = 2/4 + 2/4 = 1
June 6, 2014

Algebra
Put Hobbinton at the origin (0,0) on the x-y grid then Tom's house would be (12,-16) distance from (0,0) to (12,-16) = √(12^2 + (-16)^2) = √400 = 20
June 6, 2014

math
prob(c) = 1/4 prob(not c) = 3/4 so you are looking for c c notc = (1/4)(1/4)(3/4) = 3/64 c notc c = (1/4)(3/4)(1/4) = 3/64 notc c c = (3/4)(1/4)(1/4) = 3/64 prob of your event = 3(3/64) = 9/64
June 6, 2014

Algebra
the way you typed it, there is very little simplification I multiplied top and bottom by x^2 to get (x^3 + 3 - 36x + 3x^2)/(x^3 + 3x^2) , and that's about it. If you meant: ( (x+3/x^2 -36/(x+3)) /( (x+3)/x ) it would be something totally different. I can't guess what ...
June 5, 2014

MATH
Pick any x say, x = 0 y = 2(0)-5 = -5 ----> the point (0,-5) how about x = 4 , (or any x you feel like) then y = 2(4) - 5 = 3 --- the point (4,3) plot (0,-5) and (4,3) , join the with a straight line, extend the line to any length you feel like
June 5, 2014

math
that would be 8 - choose - 4 = C(8,4) = 8!/(4!4!) = 70
June 5, 2014

trig
For your first one, You should recognize those numbers as belonging to the 30-60-90° right-angled triangle which would make c = 1 If you didn't notice that, you could use the cosine law c^2 = 2^2 + √3^2 - 2(2)(√)cos30° = 4 + 3 - 4(√3)(√3/2...
June 5, 2014

math word problems
original: x by x area = x^2 new dimensions: (x+3) and (x+2) new area = (x+3)(x+2) = x^2 + 5x + 6 x^2 + 5x + 6 - x^2 = 46 5x = 40 x = 8 original was 8 by 8 check: old area = 64 new is 11 by 10 new area = 110 change in area = 110-64 = 46 , yeahh!
June 4, 2014

Precalculus
#3 Those are permutations since the order matters a) start with a vowel: 2*5*4 = 40 , you were right b) all consonants, means we only pick from 4 4*3*2 = 24 , you were right c) all vowels, you are right with 0 since we only have 2 vowels and we need 3 d) all consonants , ...
June 4, 2014

Math - Business Calc.
I noticed an error in Damon's solution 4th line : V = (17-2h)(5-2h)h = (17-h)(5h-2h^2) should be : V = (17-2h)(5-2h)h = (17-2h)(5h-2h^2) I had h = 1.1445
June 4, 2014

Algebra - Help!!
I did a synthetic division of x^3 - 7x + 6 by x+3 to get the other dimension of x^2 - 3x + 2 , looks like a)
June 4, 2014

Math
Where is the second equation ?
June 3, 2014

algebra math
so she need one of 10, 11, or 12 prob of that = 3/12 = 1/4
June 3, 2014

Algebra
LCD is 24x -9y/(12x) + 28y/(12x) - 2y/(12x) = 17y/(12x)
June 3, 2014

Math
x^3 - x^2 - x + 8 = 0 tough one - it does not factor tried x = ±1, ±2, ±4 , none worked so no rational root what about real roots? let f(x) = x^3 - x^2 - x + 8 for f(-1) = -1 -1 +1 +8 = 7 for f(-2) = -8 - 4 + 2 + 8 = -2 so there is a real root between -2 ...
June 3, 2014

math
Did you make a sketch? I have a right-angled triangle with a base of 15 and a height of 4, (10 ft - his 6 ft) so in relation to your angle of elevation Ø, we have the opposite and the adjacent, suggesting tanØ = 4/15 arctan = 14.93° So to the nearest degree: ...
June 3, 2014

math
PV = 25000(1.03)^-28 = $10,926.92 i = .12/4 = .03 n = 7(4) = 28
June 3, 2014

Math
the above factor of x^3 - 1 factors to (x-1)(x^2 + x + 1) the x-1 = 0 gave us x = 1 x^2 + x + 1 = 0 x = (-1 ±√-3)/2 or x = (-1 ± i√3)/2
June 3, 2014

Math
5x^4=5x x^4 - x = 0 x(x^3 - 1) = 0 x = 0 or x^3 = 1 x = 0 or x = 1 There are also two complex roots, but I don't think you have studied that. Let me know if you did.
June 3, 2014

math
second question: How can Frank be a jacket ? third question: What language is this: "what is the fraction of the amount that he that he needs to saved" What does that mean?
June 3, 2014

math 1 question!!!!!!
Didn't Ms Sue just prove to you that is is C ??
June 3, 2014

correction - math
subtract them as they sit -y = 4 y = -4 back into the first: x -3(-4) = 25 x + 12 = 25 x = 13 x = 13, y = -4 , you had them opposite.
June 3, 2014

Math
correct
June 3, 2014

Math
adults --- x girls ----- 4x boys ------5x (note x: 4x : 5x = 1 : 4 : 5) "6 more boys than girls" ---> 5x = 4x+6 x = 6 so we had 6 adults, 24 girls, and 30 boys, (satisfying all our conditions stated)
June 3, 2014

Math
nope f(-3) = (-3)^2 - 5(-3) + 1 = 9 + 15 + 1 = 25
June 3, 2014

If 12 people are playing in a tournament and?
number of subsets of 2 elements from a sample space of 12 = C(12,2) = 66
June 3, 2014

Math
yes
June 3, 2014

Math
f(4) = 16+9 = 25 g(-1) = 24-4 = 20 so what is the problem?
June 3, 2014

Math ~ Check Answers ~
use the first pair of points (2,1) and (4,0) slope = -1/2 so y = mx + b ----> y = -(1/2)x + b sub in (4,0) 0 = (-1/2)(4) + b b = 2 y = (-1/2)x + 2 use our non-used point to check: does (6,-1) lie on it? LS = -1 RS = (-1/2)(6) + 2 = -3+2 = -1 your answer is good.
June 3, 2014

Algebra 1--Please, help me!
((n-5)/(n^2 - 2n -3)) / ((n-3)/(n^2 -4n - 5)) multiply both sides by (n^2 - 2n -3)(n^2 - 4n - 5) , sometimes called cross-multiplying n^3 - 4n^2 - 5n - 2n^2+ 8n + 10 = n^3 - 2n^2 - 3n - 3n^2 + 6n + 9 -n^2 = -1 n^2 = 1 n = ± 1
June 3, 2014

word problem?
prob(going to amusement park) = 8/18 = 4/9 so number of the 225 who would go = (4/9)(225) = 100 notice Ms Sue's equation will yield the same answer.
June 3, 2014

Algebra 1
did that for you here http://www.jiskha.com/display.cgi?id=1401816411 #2, was also done somewhere, can't find it, so ... The way you typed it: 2/t + 4/3t = 4/t + 2 times 3t 6 + 4t^2 = 12 + 6t 4^2 - 6t - 6 = 0 2t^2 - 3t - 3 = 0 t = (3 ± √33)/4 somehow I don'...
June 3, 2014

Scientific notation
area = (5x10^4)(6x10^3) = 30x10^7 = 3.0 x 10^8 m^2
June 3, 2014

Probability???
yes, but I would rather have you think of (1/520)(7800) = 7800/520 ---> see, there is your division by 520 = 15
June 3, 2014

Math
|5m-11| = 9+3m case 1: 5m-11 = 9+3m 2m = 20 m = 10 case 2 -5m + 11 = 9+3m -8m = -2 m = 1/4 product of answers = 10(1/4) = 5/2 oe 2.5
June 3, 2014

Algebra 1--Please, help me!
let the amount to be added by x ml so we have 300+x ml of the new mixture .3(300+x) = .4(300) 3(300+x) = 4(300) 900 + 3x = 1200 3x = 300 x = 100 Add 100 ml of water check: Do we have the correct amount of acid? in original: .4(300) = 1200 ml in new: .3(400) = 120 ml -----> ...
June 3, 2014

Algebra/can you ck my anwers
my sum was 1770 divide that by 25 gave me a mean of 70.8 your mean of 1616 should have hit you as absurd. range is correct, your median and mode sound logical
June 3, 2014

Algebra 1--Please, help me!
#3 no need for all those brackets ... (d + 2)/(d + 8) = (-6)/(d + 8) multiply both sides by (d+8) d+2 = -6 d = -8 ahhh, trick question. Notice in the original, d≠ -8 So there is no solution. #4 correct #5 handled by bobpursley #6 (x -6)/(x^2-6) = (-4)/(x-4) x^2 - 10x + ...
June 3, 2014

Algebra 1 (Reiny)
Sorry I misread your original question So here is the correct one: right now : amount of orange juice = .25(8) = 2 cups amount of apple juice = .75(8) = 6 cups let the amount of pure orange juice to be added be x cups so just looking at the orange juice: 2 + x = .4(x+8) times ...
June 3, 2014

algebra
Bosnian was right in his first post. (think I will have a third cup of coffee to wake up)
June 3, 2014

algebra
sorry, did not register the "linear" part, and concentrated on the "increasing" actually I think it is a), the slope between any two points is 3/2 all points satisfy the equation 3x-2y=7 http://www.wolframalpha.com/input/?i=interpolate+%281%2C-2%29%2C%283%...
June 3, 2014

algebra
correct http://www.wolframalpha.com/input/?i=plot+%281%2C-3%29%2C%283%2C5%29%2C%285%2C11%29%2C%287%2C18%29
June 3, 2014

statistics
You have the subtraction backwards A score of 90 is above the mean, so the z-score should be positive z-score = (90-84)/8 = +.75
June 3, 2014

Algebra 1--Please, help me!
Argggghhh Duplicate question Didn't see that Steve had already answered it
June 3, 2014

Algebra 1--Please, help me!
cups of orange juice --- x cups of apple --------- 8-x .25x + .75(8-x) = 4.(8) 25x + 75(8-x) = 40(8) I will let you finish it 2. For your type of perfect-square trinomial the first and last terms would have to be positive. ---- the -9 takes this one out of the category. It is ...
June 3, 2014

Algebra 1--Please, check my answer!
correct
June 3, 2014

Trig
(320cos120 , 320sin120) + (35cos60 , 35sin60) you should be familiar with the trig ratios of the 30-60-90 triangle, and the multiples of those angles using the CAST rule = (320(-1/2) , 320(√3/2) + (35(1/2) + 35(√3/2) = (-160 , 160√3) + (35/2 , 35√3/2...
June 2, 2014

Algebra
Your equation doesn't even match your given data length --- x width ---- 2x - 2 area = x(2x-2) = 82 2x^2 - 2x - 82 = 0 x^2 - x - 41 = 0 use the formula ... x = (1 ± √165)/2 = appr 6.92 or some negative length = 6.92 , length = 11.85 check: 6.92x11.85 = appr 82
June 2, 2014

statistics
Looks like that professor is still giving those A's See the first 3 "Related Questions" below
June 1, 2014

algebra
let the number of boxes be x 45x + 4000 = 11200 I will let you solve this equation.
June 1, 2014

trigonometry, check please
I got 10.064.. which to the nearest tenth is 10.1
June 1, 2014

Algebra ll
hope you got -23 -48
June 1, 2014

trigonometry ans.
yes, to the nearest foot it is 66 ft
June 1, 2014

trigonometry ans.
correct in reference to your angle you are involving the opposite and the adjacent side since tanØ = opposite/adjacent your choice of tangent was correct.
June 1, 2014

algebra.can you ck my answers
216 = 6^3 <-----> log6 216 = 3 How did you ever get 0 as an answer? That is not even an equation ! I suggest you memorize the definition of logs 16-(1/4)^-2 1/2 No idea what that is supposed to be. Was that supposed to be an equation like your question suggested?
June 1, 2014

math
so the $72.09 represents 70% of the original price .7x = 72.09 x = 72.09/.7 = $102.99 check by taking off 30% of that
June 1, 2014

Math
you would have 6 equal surface areas 6x^2 = 24 x^2 = 4 x = √4 = 2
June 1, 2014

Math
length of side of the larger --- x length of side of the smaller -- y x+y = 5 So what do we see? We see 4 side faces of the larger = 4x^2 we see 4 side faces of the smaller = 4y^2 If we look straight down, we see a small face on top of the large face exposing the edge of the ...
June 1, 2014

Math
Since you already have the second part, let's work on the number of pennies , dimes and quarters we have to make $5.98 number of pennies -- x number of dimes ---- y number of quarters -- 52-x-y x + 10y + 25(52-x-y) = 598 x+10y + 1300 - 25x - 25y = 598 -24x - 15y = -702 8x...
June 1, 2014

Algebra
amount into lower rate account --- x amount into higher rate account --- 8000-x .04x + .07(8000-x) = 480 4x + 7(8000-x) = 48000 4x + 56000 - 7x = 48000 -3x = -8000 x = 8000/3 = 2666.67 amount into CD = $2666.67
June 1, 2014

Algebra 1
Since F lies on DE, all we need is the equation of DE We don't even need F slope DE = (-2-2)/(-3-3) = 2/3 so y = (2/3)x + b but (3,2) lies on it, so 2 = (2/3)(3) + b b = 0 y = (2/3) x is the equation check: F is the origin (0,0) which satisfies y = (2/3)x A rather ...
June 1, 2014

Algebra 1
#1 and #2 ok #3, I agree with you, there is little that can be done All I could see is to divide top and bottom by 2g #4 ok #5, careless error, 2/2p = 1/p , not p #6 you have a common denominator, so add them 8m^2/(4m^5) = 2/m^3 #7, according to BEDMAS, division is done in the...
May 30, 2014

Math
if arithmetic, then 8 - (5+x) = (1+2x) - 8 8 - 5 - x = 1 + 2x - 8 -3x = -10 x = 10/3 check: terms are 25/3 , 8 , 23/2 or 25/3 , 24/3 , 23/3 which is an AS
May 29, 2014

Math
Sum(all terms) = a/(1-r) = 200/(1/2) = 400
May 29, 2014

statistics
Tools like this below replace tables traditionally found at the back of textbooks http://davidmlane.com/hyperstat/z_table.html enter your mean and sd, click on "above" for "exceeds 0.83" and enter the data to get .1587 ,or .159 correct to 3 decimals
May 29, 2014

College Algebra
Your last one 3/(x-4)=7/(x-8) is the easiest of the three equations just multiply each side by (x-4)(x-8) , which is sometimes called "cross-multiplying" 7(x-4) = 3(x-8) 7x - 28 = 3x - 24 4x = 4 x = 1
May 28, 2014

College Algebra
z^2 +iz -(5+i) = (2-5i)^2 + i(2-5i) - (5+i) = 4 - 20i + 25i^2 + 2i - 5i^2 - 5 - i = 4 - 20i - 25 + 2i + 5 - 5 - i = -21 - 19i
May 28, 2014

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