Sunday

November 23, 2014

November 23, 2014

Total # Posts: 27,930

**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*

**Math**

value = 84000(.8)(.9)^4 = ....
*May 28, 2014*

**College Algebra**

(-5 - i)/(3 - 3i) = (-5 - i)/(3 - 3i) * (3+3i)/(3+3i) = (-15-15i -3i -3i^2)/(9 - 9i^2) = (-15 - 18i + 3)/(9 + 9) = (-12 - 18i)/18 = -2/3 - i (-5/2)i / ((-1/5)i ) = (-5/2) / (-1/5) = (-2/5)(-5/1) = 2 (-2i)^3 = -8i^3 now i^3 = (i^2)(i) = -i so -8i^3 = -8(-i) = 8i I do not ...
*May 28, 2014*

**College Algebra**

expand it 3.14 i - 3i^2, but i^2 = -1 = 3.14 i + 3 or in the form a+bi 3 + 3.14 i
*May 28, 2014*

**algebra**

multiply both sides by (x+7)(x+3) , some people call it cross-multiplying 5(x+3) = 3(x+7) 5x + 15 = 3x + 21 I will let you finish it from here.
*May 28, 2014*

**Math**

looks like a geometric series with a = 3 r = 2 sum(n) = a(r^n -1)/(r-1) 765 = 3(2^n - 1)/1 255 = 2^n -1 256 = 2^n 2^8 = 2^n n = 8 there are 8 terms
*May 28, 2014*

**math**

1st times 2 8x + 18y = 20 5x + 18y = 19 subtract them 3x = 1 x = 1/3 sub x = 1/3 into the 1st and solve for y to get y = 26/27
*May 28, 2014*

**Math**

yes, good job however, you should reduce 26/56 to 13/28
*May 28, 2014*

**decimals**

so the number would look like 12.ab given: a+b = 9 b is odd, a is even, b>a easy to see that a=4, b=5 or a = 2 , b = 7 or, if we count 0 as even a = 0 , b = 9 12.45 12.27 12.09
*May 28, 2014*

**MATH**

prob(pink) = 4/14 = 1/7 prob(not pink) = 1 - 1/7 = 6/7
*May 28, 2014*

**Math**

all these are standard angles for which you should know the trig ratios cos 180 = -1 , look at the cosine curve sin 90 = 1 , look at the sine curve cot 45 = 1/tan45 = 1/1 = 1 , look at your 45-45-90 triangle csc 30 = 1/sin30 = 1/(1/2) = 2 , look at the 30-60-90 triangle sec ...
*May 28, 2014*

**calculus**

I assume you meant f(x) = x √(10 - x^2) and not the way you typed it Of course the function would only be defined for -√10 ≤ x ≤ √10 f' (x) = x (1/2)(10-x^2)^(-1/2) (-2x ) + (10-x^2)^(1/2) = (10 - x^2)^(-1/2) [ -x^2 + 10-x^2] = (10-2x^2)/&#...
*May 28, 2014*

**Algebra/can you ck my answer**

correct remember , this would be statistical probability
*May 28, 2014*

**Precal, please help asap!**

let's use the sine law ... sin B/34 = sin 117°/42 sin B = 34sin117/42 = .72129... B = 46.2° or by the CAST rule B could be 133.8° But, that would mean the angle has 2 obtuse angle, which is not possible so angle B = 46.2° and there is only one triangle ...
*May 28, 2014*

**maths**

nasty and tricky the way you typed it did you mean: 3^(n-1) = 2^(n+1) ?? I sure hope so, and will assume that. take log of both sides log [3^(n-1) ] = log [2^(n+1) ] (n-1) log3 = (n+1) log2 n log3 - log3 = n log2 + log2 n log3 - n log2 = log2 + log3 n(log3 - log2) = log2 + ...
*May 28, 2014*

**Math (Pre-calc)**

1 rotation = 2π(14) or 28π inches In 1 minute he goes 280(28π) inches = 7840π inches In 1 hour he goes 60(7840π) inches = 60(7840π)/12 feet = 60(7840π)/(12*5280) miles = appr 23.3 mph sin(2π/3) = sin 120° = sin 60° = √3/2...
*May 28, 2014*

**Algebra 1**

a) is correct, but you should have brackets around the complete denominator. The way you typed it, it is only divided by (2x+10) x(x + 10)/( (2x + 10)(2x + 9) ) b) So now we have an actual numerical case and let's just follow the same argument you did in a) blacks = 5 ...
*May 28, 2014*

**math**

rise/run = 400/1600 = 1/4 = tan Ø Ø = appr 14°
*May 28, 2014*

**math**

number of sales = .2(150) = 30 commission = 6(30) = 180
*May 28, 2014*

**Algebra**

Since the positions are specific, this is a permutation, not a combination. number of ways = 33*32*31*30*29 = ...
*May 28, 2014*

**Albebra**

both numbers 2's ----> 22 less than 6 ----> 11 12 13 14 21 22 23 31 32 41 total = 10 , (not counting 22 twice) prob of your event = (36-10)/36 = 26/36 = 13/18
*May 28, 2014*

**Albebra**

that would simply be C(4,1) * C(13,5) / C(52,5) = 5148/2598960 = 99/49980 = 33/16660 = appr .00198 Note, I included the royal flush in the above, you did not say anything about exclusion. What about other hands that are both a flush and something else? e.g. what about the 4,5,...
*May 28, 2014*

**Algebra**

you want 2 out of the 4 aces prob = C(4,2)/C(52,2) = ....
*May 28, 2014*

**math help plzzz!!!!!!!!!**

-8<1-3(x-2)<13 let's just work on it as it sits -8 < 1-3x+6 < 13 -8 < 7-3x < 13 subtract 7 , (does not affect inequality sign) -15 < -3x < 6 divide by -3 , (switches the < to a > sign) 5 > x > -2 better form: -2 < x < 5
*May 28, 2014*

**math help plzzz**

the easy one first: 2(x+7)-4>5(x-3) 2x + 14 - 4 > 5x - 15 -3x > -25 x < 25/3 for the 1st, I don't know why you put brackets around the left side, since it serves no purpose did you mean 2/(5x) > 7 or (2/5)x > 7 I will assume the last case: mulitply both ...
*May 27, 2014*

**trig**

not enough information to make any distance calculations.
*May 27, 2014*

**HeLP MATH !!!!**

2.903t - 1.98 = 18 2.903t = 19.98 t = 6.88 years or 7 years from 2000 in the year 2007
*May 27, 2014*

**math**

how about cos 66° = 11.3/L L = 11.3/cos66 = appr 28 ft
*May 27, 2014*

**Math**

log7 49(3√(x^5) ) = log749 + log73 + log7 x^(5/2) = 2 + log7 3 + (5/2)log7 x it can't be evaluated unless you give me a value for x
*May 27, 2014*

**math**

You don't need an "angle of elevation formula" Just make a sketch and use your basic trig ratios I see it as tan Ø = 350/1000 = .35 Ø = appr 19.26°
*May 27, 2014*

**hectorr**

Why do you call this a fractional equation ? I see no fraction in the equation. 3[2x-(x+7)]=5(x-3) 3[x-7] = 5x - 15 3x - 21 = 5x - 15 -2x = 6 x = -3 check: if x = -3 LS = [3(-6 - 4] = 3[-10] = -30 RS = 5(-6) = -30 = LS my solution is correct.
*May 27, 2014*

**trig length**

Make a sketch to see that sin 69° = 603/L L = 603/sin69 = appr 562.95 m
*May 27, 2014*

**6th grade math**

a) let x=0 is 4(0) - 5 < 3 -5 < 3 ???, YES ... d) let x = 4 is 4(4) - 5 < 3 16 - 5 < 3 11 < 3 ??? , NO do the others the same way
*May 27, 2014*

**maths**

By the definition of logs loga b = c <------> a^c = b so if log10( (5x-1)/(x-2) ) = 2 , then 10^2 = ( (5x-1)/(x-2) )
*May 27, 2014*

**maths**

log(5x-1) = 2 + log(x-2) log(5x-1) - log(x-2) = 2 log ( (5x-1)/(x-2) ) = 2 (5x-1)/(x-2) = 10^2 = 100 100x - 200 = 5x-1 95x = 199 x = 199/95
*May 27, 2014*

**math**

since it is parallel it must look like this: 3x - 4y = c, that is, it will differ only in the constant plug in your given point, find c, and you are done
*May 27, 2014*

**math**

the only numbers divisible by 5 from 1 to 35 are 5,10,15,20,25,30, and 35 there are 7 of them prob of your stated event = 7/35 = 1/5
*May 27, 2014*

**geometry**

the arc-length can be found this way arc = rØ, where r is the radius and Ø is the angle in radians. 92/180 = Ø/π Ø = 92π/180 16 = r(92π/180 r = 16(180)/(92π) = appr 9.96 units check: 92° is very close to a right angle, so the...
*May 27, 2014*

**math**

correct
*May 25, 2014*

**math**

I assume you meant (x+2)/2 = 4/x multiply each side by 2x , (sometimes called cross-multiplying) x^2 + 2x = 8 x^2 + 2x - 8 = 0 (x+4)(x-2) = 0 x = -4 OR x = 2 , which is choice 2) (if the way they presented the answer used the word AND, they they are technically incorrect. x ...
*May 25, 2014*

**Math - Personal Finance**

To use the formula for a series of payments, such as carpayments, and mortgages, the period of compounding and the period of payments must be the same. Yours has the interest compounded semi-annually, and the payments are monthly, which does not match up So we have to find the...
*May 25, 2014*

**math**

looks like tan Ø = 169/500 = .338 Ø= appr 19°
*May 25, 2014*

**Algebra 1**

dh/dt = -32t + 148 = 0 for a max of h 32t = 148 t = 148/32 = 4.625 when t = 4.625 h = -16(4.625)^2 + 148(4.625) + 3 0 = 372.25 looks like d
*May 23, 2014*

**Algebra**

I think you are referring to one of the alternate ways to represent a combination see: http://laurashears.info/math122/unit5/notation/ Steve found the value of each of your combinations, so just multiply them 84*15*3 = .......
*May 22, 2014*

**Geometry**

I will assume you meant (x + 6)^2 + (y + 4)^2 = 36 , ( notice how the exponent is shown ) which is a standard equation of a circle with centre at (-6,-2) and a radius of 6 units Just noticed that I answered the same question back in 2012 http://www.jiskha.com/display.cgi?id=...
*May 22, 2014*

**Algebra 2**

I will assume that your light is parabolic and the bulb is placed at its focal point The standard form of the equation with vertex at the origin and focal point (p,0) is y^2 = 4px so you have a focal point of (6,0) then y^2 = 24x is our equation if the diameter is 36 inches, ...
*May 22, 2014*

**HELP!!!! MATH**

Did you make your sketch? If the depth is y you should see that h/24 = cos15° h = 24cos15 = appr 23 ft
*May 22, 2014*

**math**

number of participants --- x number passed first part = 7x/8 (failed = 1/8, so passed = 7/8) number who passed 2nd test = (2/7)(7x/8) = (1/4)x so 1/4 of the original passed the exam check: suppose 56 took the test so 49 passed of those (2/7)(49) or 14 passed 14/45 = 1/4
*May 22, 2014*

**math**

let the number of red marbles be x number of green marbles = (1/3)x = x/3 yellow marbles = 6x red : green : yellow = x : x/3 : 6x = 3x : x : 18x for a total of 24x so yellows would be 18x/24x = 3/4 of his collection
*May 22, 2014*

**geometric**

Next time you are near a big truck, you will notice that most of the trailers will have the notation 53' written along the side, showing that the standard length of the trailer is 53 feet. It asked for the customary way, so it is feet.
*May 22, 2014*

**calculus**

Wolfram amazes me more every day. http://www.wolframalpha.com/input/?i=area+between+y%3D+ln%281-x%29+%2C+y%3D3+%2C+x%3D0 notice that Damon took horiontal slices, while Wolfram took vertical slices. Same result of course.
*May 22, 2014*

**math**

So the length of the base of the continuous rectangle = 10(2) + 10(4) = 60 inches so the distance around the whole thing = 2(60) + 2(3) = 126 inches
*May 22, 2014*

**trig**

make a sketch to see that sin10° = height/35 height = 35sin10 = appr 6.1 ft
*May 22, 2014*

**math**

Let the distance run by the dog be 7x m let the distance run by the cat be 4x m so 7x = 4x + 12 3x = 12 x = 4 So the dog has to run 7(4) or 28 m to catch the cat. check: In the same time that the dog ran 28 m , the cat ran 16 m but the cat had a 12 m head-start , giving us ...
*May 22, 2014*

**Algebra where did I go wrong**

Mark, the correct answer is 10 Please trust Damon.
*May 22, 2014*

**Algebra**

prob (2 yellow) = (6/15)(6/15) = 36/225 = 4/25 Since you are returning the first marble picked, the second probability is the same as the first one.
*May 21, 2014*

**Precalculus**

I followed your description ok. so we get: -8 + 2x + 15 = 9 2x = 2 x = 1 10 + 3x + 25 = 38 3x = 3 x = 1 , confirming our first answer 4 - 3x + 5 = y 4-3+5=y y = 6 So x = 1 , y = 6
*May 21, 2014*

**algebra**

let d be the number of DVD's rented 2d + 6 = 48 2d = 42 d = 21 If the customer borrows less than 21 DVD's the first plan is better If the customer borrows 21 DVD's s, the cost is the same If the customer borrows more than 21, the flat rate of $48 is best.
*May 21, 2014*

**math (last question #5) @Damon**

if c is 8y^2 - 10y + 3 , then yes.
*May 21, 2014*

**Math 8th gr.**

27 - (-9) (-2) ÷ 3 * (-4) - 0 - 33 - (-39) just follow the rule of operations ... 27 + 24 - 0 - 33 + 39 = 57
*May 21, 2014*

**MATH**

makes no sense. We don't know the distribution of boys to girls in the 12 middle schoolers.
*May 21, 2014*

**maths**

yes, what about it? The statement is true.
*May 21, 2014*

**math test**

Pacific = x Caribbean = x+32 Medi = 4x - 38 x+x+32+4x-38 = 828 you solve it, it is easy
*May 21, 2014*

**Calculus**

so one side is not needed. let the two width be x m let the one length be y m 2x + y = 1000 y = 1000 - 2x area = xy = x(1000-2x) =1000x - 2x^2 d(area)/dx = 1000 - 4x = 0 for a max of area 4x = 1000 x = 250 y = 1000-500 = 500 max area = xy = 250(500) = 125000 m^2
*May 21, 2014*

**Calculus**

dd/dt = 1200 - 72000t = 0 for a max 72000t = 1200 t = 1/60 d = 1200(1/60) - 36000(1/3600) = 10 m
*May 21, 2014*

**Algerbra 2**

ummhhh, value in 6 years = 118000(1.09)^6
*May 20, 2014*

**Algerbra 2**

value in 6 years = 118000(1.09)^6 = ....
*May 20, 2014*

**Algebra**

total = 2x+1 + 3x + x+2 = 6x + 3 prob red = (2x+1)/(6x+3) = (2x+1)/(3(2x+1) ) = 1/3
*May 20, 2014*

**math**

FF -- x DD -- y RR -- z x+y+z = 41.70 , #1 2x + z = 37.95 , #2 x+y = 26.75 , #3 #1 - #3" z = 14.95 sub into #2 2x + 14.95 = 37.95 2x = 23.00 x = 11.50 sub into #3 11.50 + y = 26.75 y = 15.25 FF costs 11.50 DD costs 15.25 RR costs 14.92
*May 20, 2014*

**Math**

your slope of -2/5 or -.4 for line AB is correct The slope of a line can be any real number, both positive and negative If the slope is positive the line leans to the right If the slope is negative the line leans to the left if the slope is zero, the line is horizontal.
*May 20, 2014*

**Precalculus**

Since you are given the slope and the y-intercept, the problem becomes a matter of just subbing in the values y = (5/8)x + 4
*May 20, 2014*

**Algebra**

19 P 2 = 19!/(19-2)! = 19(18)(17!)/(17! = 19(18) = 342 If by "if there is no r" you mean "if the value of r = 0" then 4P0 = 4!/(4-0)! = 1
*May 20, 2014*

**Algebra**

Damon, I think you forgot to divide by 7 before taking the square root. SD = √(80/7) = 3.3806 The amazing Wolfram supports this http://www.wolframalpha.com/input/?i=standard+deviation+4%2C+8%2C+5%2C+12%2C+3%2C+9%2C+5%2C+2
*May 20, 2014*

**geometry**

So you need the length of the hypotenuse sin 13° = 186/x x = 186/sin13° = 826.8 ft
*May 20, 2014*

**algebra**

width --- x length -- 2x+4 x(2x + 4) = 400 2x^2 + 4x = 400 x^2 + 2x = 200 x^2 + 2x + 1 = 200 + 1 (x+1)^2 = 201 x+1 = ± √201 x = -1± √201 x = appr 13.18 cm or a negative, which we will reject The width is appr 13.2 and the length is appr 30.4
*May 20, 2014*

**math homework help**

PV = 125000(1.03)^-5 = $107,826.10
*May 20, 2014*

**Math: Linear Equation**

A linear equation of your type will produce a straight line when graphed. So all you need are 2 distinct points. Using the x and y intercepts are a quick and easy way to do this, after all the intercepts are just plain ol' points. Here is an easy way to do this: let x = 0 ...
*May 20, 2014*

**math**

distance = 7(55) miles = 385 miles number of gallons of gas = 385/30 = appr 12.8 or 13 gallons
*May 20, 2014*

**no**

3 undecillion http://www.thealmightyguru.com/Pointless/BigNumbers.html in scientific notation: 3.0 x 10^36 A rather large number, considering that the total number of grains of sands are estimated to be only about 7.5 x 10^18 and Carl Sagan claimed that there are more stars in...
*May 20, 2014*

**Math**

I even tried this to see the median answer http://www.wolframalpha.com/input/?i=sort+19%2C+19%2C+14%2C+14%2C+16%2C+19%2C+19%2C+16%2C+16%2C+15%2C+17%2C+16%2C+17%2C+16%2C+15%2C+14%2C+15%2C+15%2C+17%2C+14%2C+16%2C+15
*May 20, 2014*

**Math**

Wow, I didn't know that Wolfram does even this stuff This wonderful webpage amazes me more all the time. http://www.wolframalpha.com/input/?i=mean+19%2C+19%2C+14%2C+14%2C+16%2C+19%2C+19%2C+16%2C+16%2C+15%2C+17%2C+16%2C+17%2C+16%2C+15%2C+14%2C+15%2C+15%2C+17%2C+14%2C+16%2C+...
*May 20, 2014*

**statistics**

prog(right) = 1/5 prob(wrong) = 4/5 prob of your stated event is, getting none right --> C(12,0)(1/5)^0 (4/5)^12 = .0687 getting one right --> C(12,1) (1/5) (4/5)^11 = .20616 getting two right --> C12,2) (1/5)^2 (4/5)^10 = .2835 getting three right --> C(12,3) (1/5...
*May 20, 2014*

**Algebra**

z-score = (given value - mean)/sd -1.7 = (13 - 18.1)/sd -1.7sd = -5.1 sd = -5.1/-1.7 = 3
*May 19, 2014*

**Need help with pre cal hw**

1. I sketched a triangle, and noticed I could use the cosine law: R^2 = 8^2 + 6^2 - 2(8)(6)cos 50° = 38.2923... R = appr 6.189 km or use vectors first vector = (8cos30 , 8 sin 30) = (6.9282 , 4) 2nd vector = (6cos160, 6sin 160) = (-5.63815.. , 2.05212) sum = ( 1.29004...
*May 18, 2014*

**math**

a reflection across the y-axis causes the x value to become opposite, while the y stays the same using your wording: (x,y) ----> (-x + 1, y - 2) A(1 , -3) ----> A' (0, -5) B(4 , -5) ----> B' (-3 , -7) C(3 , -1) ----> C' (-2 , -3) You should really have ...
*May 18, 2014*

** RE-TYPE**

Oh no, log6 is not a number, it is an operator. You can't factor out log6 (that would be doing something like √8 - √3 = (√)(8-3) ) You have to use your rules of logs. log6(x+3) - log6(x-5) = 2 log6 ( (x+3)/(x-5) ) = 2 which by definition is (x+3)/(x-5) = ...
*May 18, 2014*

**Calculus**

Oh no, 6 is not a number, it is an operator. You can't factor out 6 (that would be doing something like √8 - √3 = (√)(8-3) ) You have to use your rules of logs. 6(x+3) - 6(x-5) = 2 6 ( (x+3)/(x-5) ) = 2 which by definition is (x+3)/(x-5) = 6^2 = 36 36x - ...
*May 18, 2014*

**Calculus**

log5 16807^5 - log57^3 = log5A log5 (16807^5/7^3) = log5A A = 16807^5 / 7^3 = 49(16807)^4 = appr 3.91 x 10^18
*May 18, 2014*

**maths**

I strongly recommend that you mind your p's and q's
*May 18, 2014*

**Calculus**

The way you typed R(t), we have to read it as R(t) = 9/2.718 ( t(t-3)^3) then R' (t) = (9/2.718) [ t (3)(t-3)^2 + (t-3)^3 ] = (500/151)(t-3)^2 ( 3t + t-3) = (500/151)(4t - 3)(t-3)^2 How did the base of (t-3) suddenly turn into (t-4) ?
*May 17, 2014*

**algebra**

balance on home = .08(118,000) = $94,400 i = .095/12 = .00791666... n = 30(12) = 360 paym( 1 - 1.00791666..^-360)/.00791666.. = 94400 payment = $793.77
*May 17, 2014*

**algebra**

a) since 0% interest, the monthly payment would simply be 42500/60 = $708.33 b) I believe in the US , add-on-interest is done this way: amount to be financed = 42500-5100 = 37400 interest = 37400(.025)(5) = 4675.00 total of loan = 37400 + 4675 = 42075.00 monthly payment = ...
*May 17, 2014*

**math**

Unfortunately , the expression and measurement of time is not metric, so we have to make some changes. (similar to the US method of working in miles, yards, feet and inches) (14 hrs, 3 min)/3 = (13 hrs, 63 min)/3 = 4 1/3 hrs, 21 minutes = 4 hrs, 20 min , 20 min = 4 hrs and 41 ...
*May 17, 2014*

**math**

Does it fit the description I gave you? How about some thinking on your part after all your posts ?
*May 17, 2014*

**math**

in a reflection in the x-axis, all the x values stay the same, but the new y's become opposites of the old ones now, which matches that description.
*May 17, 2014*

**math**

prob(under 25) = .55 prob(over 25) = .45 prob (exactly 4 of 6 are under 25) = C(6,4) (.55)^4 (.45)^2 = .27795
*May 17, 2014*

**Math**

(-8x)(3x^2) = -24x^3
*May 17, 2014*

**math**

10 ---> 1 , looks like it went left 9 3 ---> 6 , looks like it went up 3
*May 17, 2014*

**math**

just evaluate y for the given x's and plot the points e.g , when x = -2 y = (1/3)(2) - 2 = 2/3 - 2 = -4/3 ------> so you have the point (-2, - 4/3
*May 17, 2014*

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