Thursday

November 26, 2015
Total # Posts: 31,843

**Math**

kim's present age --- x mom's present age -- 47 in 5 years: kim's age == x+5 mom's age == 52 52 = 2(x+5) + 10 52 = 2x + 10 + 10 x = 16 Kim is now 16 check: in 5 years , Kim is 21 Mom is 52 what is twice 21 + 10 ?? ,,, mmmh, I get 52
*September 10, 2015*

**Math**

645.0m/s = 38700 m/min = 2322000 m/hr 1 miles = 1609.34 m = (2322000/1609.34) miles/hr = 1442.8 mph
*September 10, 2015*

**mathematics**

using our basic formulas S(11) = (11/2)(4 + 10(3)) = 187 t2 = ar = -6 t5 = ar^4 = 48 divide them: r^3 = 48/-6 = -8 r = -2 in ar = -6 a = 3 sum(4) = a(r^4 - 1)/(r-1) = 3((-2)^4 - 1)/(-2-1) = 3(15)/-3 = -15 check: first 4 terms are: 3 , -6, 12, -24 add them to get -15
*September 10, 2015*

**math**

horizontal line has form y = c vertical line has form x = k looking at the point(5,7) ----> y = 7
*September 10, 2015*

**math**

should have been -1/2a - a and you also dropped the b in 8 3/4b I am not crazy about the solution done in parts. Better form would be – ½ a + ¾ b – (a – 8b) = -1/2a + 3/4b - a + 8b = -1/2a - a + 8b + 3/4b = -3/2a + 35/4b or = -1 1/2a + 8 3/4b
*September 10, 2015*

**mathematics**

speed of busA --- x km/h speed of busB ---(x+10) km/h time for busA = 300/x time for busB = 300/(x+10) 300/x - 300/(x+10) = 5/4 times 4x(x+10) 1200(x+10) - 1200x = 5x(x+10) 1200x + 12000 - 1200x = 5x^2 + 50x 5x^2 + 50x - 12000 = 0 x^2 + 10x - 2400 = 0 by formula: x = 44.24 or ...
*September 10, 2015*

**math**

4a – 5b + 2a – b^2 = 6a - 5b - b^2 = 24 - 5(-1) - (-1)^2 = 24 + 5 - 1 = 28 you are right , notice I simplified by algebra first, makes no difference which way
*September 10, 2015*

**Pre-ALgreba**

It looks like you have a right-angled triangle with hypotenuse of 12 and a base of 10 h^2 + 10^2 = 12^2 h^2 + 100 = 144 h^2 = 44 h = √44 = appr 6.6
*September 10, 2015*

**Intermediate Algebra (math)**

m = 2rg^2 – 5rx 5rx = 2rg^2 - m x = (2rg^2 - m)/(5r)
*September 10, 2015*

**Calculus**

LS = cos(3x) = cos(2x+x) = cos(2x)cosx - sin(2x)sinx = (2cos^2 x - 1)(cosx) - 2sinxcosxsinx = 2cos^3 x - cosx - 2(sin^2x)cosx = 2cos^3 x - cosx - 2(1 - cos^2 x)cosx = 2cos^3 x - cosx - 2cosx + 2cos^3 x = 4cos^3 x - 3cosx = RS
*September 10, 2015*

**New holy ganges public school (Khagaria , bihar)**

number correct --- x , where 0 ≤ x ≤ 13 number incorrect --- y number not answered 13-x-y 5x - 2y + 0(13-x-y) = -5 5x - 2y = -5 we need integer solutions for this equation y = (5x + 5)/2 the numerator must be even, so x must be odd if x=1, y=5 if x = 3, y = 10 if x...
*September 10, 2015*

**math urgent**

I entered your identity in the Google search window and got all kind of solutions. Here are the first two: https://in.answers.yahoo.com/question/index?qid=20140221115147AA0ejyo http://www.meritnation.com/ask-answer/question/prove-that-tana-2tan-2a-4tan4a-8cot8a-cota/...
*September 10, 2015*

**Math**

fuel used to go 180 miles = 5/8 tank - 2/8 tank = 3/8 tank so to go 200 miles, he would use (3/8)(200/180) tanks = 5/12 of the tank total used = 3/8 tank + 5/12 tank = 19/24 tank so he must top up his tank by the total he used which is 19/24 of the tank. but he has 1/4 tank ...
*September 10, 2015*

**algebra 1**

It is hard to see the chart you made, since it is very difficult in this format to create proper columns. All I can suggest is to carefully look at your previous examples from class and fill in the required data for each of the questions. Both Ms Sue and I gave you acceptable ...
*September 9, 2015*

**Math**

Yes, they are both 0, but your reasoning baffles me what is " cos(t) = x" supposed to mean ? The hint was to use the period 9π/2 = 4π + 1/2 π so we have 2 full rotations plus another half cos(9π/2) = cos(π/2) = 0
*September 9, 2015*

**probability**

possible outcomes: MH HM HH --- allowing for the case they both hit it prob = (.8)(.75) + (.2)(.25) + (.2)(.75) = .... you push the buttons
*September 9, 2015*

**grambling ???**

3√192 --- find factors of 192 one of them a perfect square , namely 64 x 3 = 3√64 √3 = 24√3
*September 9, 2015*

**probability**

perfect case for a Venn diagram solution draw 3 intersecting circles, and fill in the data add up all the entries, 100 - (above sum) is the number who don't read any of the three
*September 9, 2015*

**Math**

could have been: 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 whose sum adds up to 13 ?
*September 9, 2015*

**algebra**

Wow, no wonder you guys are confused. How to complicate a simple question ! It does work, but ...... "old-fashioned way" 8 inches per 5 second = 96 inches/min = 5760 inches/hour -- and there are 5280x12 or 63360 inches per mile = (5760/63360) miles/hr = .0909.. miles/hr
*September 9, 2015*

**algebra**

Why don't you type one of the examples that your teacher gave you in "chart format" so we can see what you need ?
*September 9, 2015*

**algebra**

you mean something like this ..... ??? 18000 gallons ---- 144000 pints 40 hours ------ 2400 minutes ----(144000/2400) pint/min to get 60 pints/min If you look above that is exactly what I did just fill in the places in your "chart"
*September 9, 2015*

**algebra**

I am not familiar with the "chart format" your teacher is using. I solved it the way I used to teach this kind of problem.
*September 9, 2015*

**algebra**

I would do it this way: 18000 gallons in 40 hrs = 450 gallons/hr ---- divide by 40 = 3600 pints/hr ----- there are 8 pints in a gallon = (3600/60) pints/min ---- there are 60 min in 1 hr = 60 pints/min or the way Ms Sue suggested 18000 gal = 144000 pints 40 hrs = 2400 minutes...
*September 9, 2015*

**algebra**

how about this approach: 10 cm/sec = 600 cm/minute = 36000 cm/hr 1 ft = 12 x 2.54 cm = 30.48 cm so 36000 cm/hr = (36000/30.48) ft/hr = 1181.102... you were right.
*September 9, 2015*

**Math**

How about just memorize that 8x7 = 56
*September 9, 2015*

**math**

.15(30) +.60x = .36(x+30) solve for x
*September 9, 2015*

**math**

I don't see an error
*September 9, 2015*

**Calculus and Vectors**

You are running into what is called the "ambiguous case" . For example sin 30° = sin 150° = .5 because the sine is positive in the II and III quadrant. So If you start with sinØ = .5 your calculator is programmed to always give the closest angle to 0, ...
*September 9, 2015*

**Math**

f(Ø) = -2sin(4(Ø+45))-1 amplitude: 2 period = 360°/4 = 90° or π/2 Phase shift: 45° to the left vertical shift: down 1
*September 9, 2015*

**Math**

1/3 of 45 is 15 so 15 females were in the jump there were 100 females Use your formula for "conditional probability" found in your text or your notebook and plug in
*September 9, 2015*

**Math**

Since starting with 0 would not make it a 3-digit number, we have only 6 choices for the lead digit so number of cases = 6 x 6 x 5 = 180
*September 9, 2015*

**Calculus**

when t = 2, y = 40(2) - 16(4) = 16 when t = 2.5 , y = 40(2.5) - 16(2.5^2) = 0 avg velocity = (0-16)/(2.5-2) = -32 ft/s
*September 9, 2015*

**Math**

since cscØ = 1/sinØ csc (2π/5) = 1/sin(2π/5) How did you get the second one correct but miss the first one ?
*September 9, 2015*

**Math**

1. I get 1.05146 2. ok
*September 9, 2015*

**algebra**

distance by car --- x miles distance by copper -- 250-x miles x/45 + (250-x)/120 = 3 each term times 360 , the LCD 8x + 3(250-x) = 1080 8x - 3x = 330 x = 66 I will let you finish it
*September 9, 2015*

**Math**

from the first: y = 4x+9 sub into the 2nd: 3(4x+9) - 2x = 7 12x + 27 - 2x = 7 10x = -20 x = -2 you had that, but you only found x, you must also find y sub x = -2 into y = 4x+9 y = -8+9 = 1 x = -2, y = 1
*September 9, 2015*

**Algebra**

day1 = 30+2 day2 = 30+2(2) day3 = 30+3(2) ... day10 = 30+10(2) ... day22 = 30+22(2) = 74 Doesn't 660 seem totally illogical?
*September 9, 2015*

**math urgent**

number of votes cast --- x .54x = 250 x = 250/.54 = .... round to the nearest whole number
*September 9, 2015*

**math 4**

What is 3/24 reduced to lowest terms?
*September 9, 2015*

**physics**

first ball distance = -4.9t^2 - 15.6t + 21.4 vel ball1 = -9.8t - 15.5 at ground: 0 = -4.9t^2 - 15.6t + 21.4 or 4.9t^2 + 15.6t - 21.4=0 by formula: t = 1.035 seconds or some negative t vel at that time = -9.8(1.035) - 15.5 = -25.64 m/s magnitude is 25.64 m/s 2nd ball distance...
*September 9, 2015*

**PHYSICS**

Is there any reason why you would repeat your post, after it had already been answered ? http://www.jiskha.com/display.cgi?id=1441709813
*September 9, 2015*

**precalc**

if you meant y = 16x^2 + 8x - 1 x of the vertex is -8/32 = -1/4 y = 16(1/16) + 8(-1/4) - 1 = -2 vertex is (-1/4), -2) and the parabola opens up the domain of any "vertical" parabola is x is any real number confirmation: http://www.wolframalpha.com/input/?i=y+%3D+16x%...
*September 8, 2015*

**geometry**

let the other end be v(x,y) (x+3)/2 = 5 x+3 = 10 x = 7 find the y of the endpoint in the same way
*September 8, 2015*

**calculus**

D(C(x)) = D(4x-5) = (4x-5)^2 + 2(4x-5) expand and simplify if necessary f(x) = 1 + 3√(x+2) f(f(x)) = 1 + 3√(x+2) = 1 + 3√((1 + 3√(x+2))+2) = 1 + 3√(3 + 3√(x+2) ) testing: let x = 2 f(2) = 1 + 3√4 = 7 f(7) = 1 + 3√9 = 10 f(f(2)) ...
*September 8, 2015*

**MATH HELP**

(2√3)(2√6) = 6√18 = 6√9 √2 = 18√2 , still irrational are you guessing? What makes you think this one, and the last one, is rational
*September 8, 2015*

**Precalc**

no, since h(x) = 7, it means no matter what you put in for x, the answer will be 7 so h(D(x)) = 7
*September 8, 2015*

**Precalc**

As I noted before, I don't like your notation Does h(D) mean h(D(x)) or (h◦D)(x) ? Those are standard notation .
*September 8, 2015*

**math**

2√3 + 3√3 = 5√3 which is still irrational
*September 8, 2015*

**Math**

amount of the 25% stuff --- x ml amount of the 10% stuff --- 500-x ml .25x + .1(500-x) = .2(500) solve for x
*September 8, 2015*

**precalc**

your notation should say D(x)/E(x) = (x^2 + 2x)/(-2(5x-1)) or = (x^2 + 2x)/(-10x + 2)
*September 8, 2015*

**math**

I assume you mean |-3| the | | stands for absolute value, that is, we always take the positive value of whatever is inside the two bars. so |-3| = 3 and of course |3| = 3 so |5-9| = 4 , and |9-5| = 4 so if you have an equation such as |2x - 7| = 5 we have two solutions, 2x-7...
*September 8, 2015*

**Algebra**

take the 2nd and divide by the 1st: (1/5) ÷ 1 = 1/5 should be the same as the 3rd divided by the 2nd: (1/25) ÷ (1/5) = (1/25)(5/1) = 1/5 looks like r = 1/5 sum(all terms) = a/(1-r) = 1/(1-1/5) = 1/(4/5) = 5/4
*September 8, 2015*

**copy error - Math**

I have a copy error, should have been solve 2x^2 - 10x = -3 2x^2 - 10x + 3 = 0
*September 8, 2015*

**Math**

solve 2x^2 - 10x = 3 2x^2 - 10x - 3 = 0 which methods have you learned to solve a quadratic?
*September 8, 2015*

**Math**

Since the cosine is negative in quads II or III, the answers would be 120° or 240°
*September 8, 2015*

**Math**

2cosx - 1 = 0 2cosx = 1 cosx = 1/2 I know from my basic trig relations that cos 60° = 1/2 and by the CAST rule cos 300° = 1/2 so x = 60° or x - 300° , or in radians: π/3, 5π/3 2cosx = 0 cosx = 0 I know from looking at a cosine curve that x = 90° ...
*September 8, 2015*

**math**

go with that, although x-54 does not acknowledge that x could be less than 54. In that case the difference would be a negative number, that is why I placed absolute value signs around the x-54
*September 8, 2015*

**math**

I don't know what your choices are, but if the number is x, I would expect to see |x-54|
*September 8, 2015*

**Math**

You have now posted this question 5 times. Both Damon and I have answered it, and you claim that you do not understand the method I used. http://www.jiskha.com/display.cgi?id=1441676620 I used the standard method for this type of question. based on the simple fact that (a+b)^2...
*September 8, 2015*

**Trigonometry**

make a sketch by drawing in the height, calling it h by Pythagoras: h^2 + 15^2 = 20^2 h^2 = 175 h = √175 area = (1/2) base x height = (1/2)(30)√175 =.... for angle: tanØ = √175/15 I get Ø to be appr 41.4°
*September 8, 2015*

**MATH**

what is 30000(1.12)^5 ? (and let me know where I can make that investment)
*September 8, 2015*

**MATH**

just follow the rules of exponents to get 9a^2 b^-2 _________ (3a^-2b)^-1 = (9a^2 b^-2)(3a^-2b) = 27 a^0 b^-1 = 27/b
*September 8, 2015*

**science**

One diameter covers 28π cm So in 1 minute the rim covers 2020(28π) cm so the linear speed of the rim = 56560π cm/min
*September 8, 2015*

**MATH**

(2^-1 + 3^-1)^2 = (1/2 + 1/3)^2 = (5/6)^2 = 25/36
*September 8, 2015*

**Maths**

dimension of the box is 60-2x by 60-2x by x , where x < 30 Vol = x(60-2x)^2 = 3600x - 240x^2 + 4x^3 d(Vol)/dx = 3600 - 480x + 12x^2 = 0 for a max/min of Vol divide each term by 12 x^2 - 40x + 300 = 0 (x-10)(x-40) = 0 x = 10 or x = 40, but x<30 x = 10 cut out flaps of 10 ...
*September 8, 2015*

**Math-Help Please**

#2 job needs 25 man-hours to complete. so if 3 men work, number of hours = 25/3 hrs, or 8 hours and 20 minutes
*September 7, 2015*

**Math-Help Please**

distance = 65(50/60) = 325/6 km rate needed to have a time of 40 minute = (325/6) / (40/50 = (325/6)(5/4) = 1625/24 km/h or appr 67.7 km/h
*September 7, 2015*

**math/physics**

f(t) = −16t^2 + 96t when it hits the ground, f(t) = 0 -16t^2 + 96t = 0 t^2 - 6t=0 t(t-6) = 0 t = 0 , we knew that or t = 6 so it hits the ground after 6 seconds b) find the vertex of f(t) = -16t^2 + 96t c) see b)
*September 7, 2015*

**math**

amount at 5% --- x amount at 6% --- 800-x solve for x .05x + .06(800-x) = 43
*September 7, 2015*

**Math**

Who is it, Michael or Emma ? http://www.jiskha.com/display.cgi?id=1441674868
*September 7, 2015*

**Math**

(9p + 7qi)(9p - 7qi) , where i^2 = -1 Look below at the Related Questions, when you asked it as a difference of squares.
*September 7, 2015*

**Math**

What part of my answer to the same question I gave you yesterday did you not like ?? http://www.jiskha.com/display.cgi?id=1441513440
*September 7, 2015*

**Math**

distance between two towns --- x miles time for first trip = x/35 time for 2nd trip = x/40 x/35 + x/40 + 15 = 41 LCD = 280 8x + 7x = 7280 x = 485 1/3 miles
*September 7, 2015*

**algebra**

Is your sketch a right-angled triangle with sides 4x, 4(x+10), and a hypotenuse of 368.78 ? I see it as (4x^2) + (4x+40)^2 = 368.78^2 use the quadratic formula to solve for x
*September 7, 2015*

**geometry**

base --- x height --- x+25 (1/2)(x)(x+25) = 625 x^2 + 25x = 1250 x^2 + 25x - 1250 = 0 (x-25)(x+50) = 0 x = 25 or an inadmissible negative
*September 7, 2015*

**Math**

width of pavement --- x ft original plot has area of 342 ft^2 inside part is 18-2x by 19-2x, where x > 9 (18-2x)(19-2x) = 110 342 - 74x + 4x^2 = 110 4x^2 - 74x + 232 = 0 2x^2 - 37x + 116 = 0 (x-4)(2x - 29) = 0 x = 4 or x = 29/2 = 14.5 the pavement should be 4 ft wide check...
*September 7, 2015*

**math**

the "dominating" term is -10x^3 , not 10x^3 so as x → +∞ , -10x^3 → -∞ , and as x→ -∞ , -10x^3 → +∞ general appearance ... http://www.wolframalpha.com/input/?i=f%28x%29+%3D+1000+%E2%88%92+39x+%2B+51x%5E2+%E2%88%92+10x%5E3+
*September 7, 2015*

**Algebra**

correct
*September 7, 2015*

**Math Urgent**

the part of the circle not covered by any part of the other two.
*September 7, 2015*

**Math Urgent**

best done with Venn diagram draw 3 intersecting circles, place x in the intersection of all three since we are not given that number look at the intersection of any two circles. We already have x in the middle, so place 4 in each of the remaining region of the pairs now go to ...
*September 7, 2015*

**math**

let the width be x ft dimensions of the factory are: 210-2x by 280-2x So what is the area of the factory ? set that equal to 1/2 the area of the lot and solve that quadratic
*September 7, 2015*

**algebra**

What a convoluting question. Here is how I would word this question. 1. is 25/18 terminating or repeating ? --- repeating 2. is 8x25/15 terminating or repeating? ---- repeating 3. is any number divided by 20 terminating or repeating ? ---- terminating 4. which of the following...
*September 7, 2015*

**Trigonometry**

Left Side = sinØ(1/cosØ + 1/sinØ) = sinØ(sinØ + cosØ)/(sinØcosØ) = (sinØ + cosØ)/cosØ RS = sinØ/cosØ + 1 = (sinØ + cosØ)/cos‚ = LS
*September 7, 2015*

**math**

the 8 in38,234= 8000 the 8 in 37,825 = 800 So the first is 10 times greater than the second
*September 7, 2015*

**Pre Cal**

nice, bob posted this question 3 times and each time there was a change in the way he typed it.
*September 7, 2015*

**Pre Cal**

Ok, now that you have changed it again .... but still have the denominator as ambiguous. I will read it as ( (2x^-4y^-1)(2y^4z^-1) )^-2/(2yx^3z^0) (4x^-4 y^3 z^-1)^-2 /(2y x^3) = (1/16)(x^8 y^-6 z^2)/(2y x^3) = (1/32)(x^5 y^-7 z^2 or = x^5 z^2/(32y^7)
*September 7, 2015*

**math**

Just did this, you tacked in on at the end of your last posting. Look there
*September 7, 2015*

**math**

I assume we are doing a new question and f(x) = x^2 - 1 , g(x) = 2x + 2 then (fg)(x) = f(g(x)) = f(2x + 2) = (2x + 2)^2 - 1 = 4x^2 + 8x + 4 - 1 = 4x^2 + 8x + 3 test with some value, say x = 3 g(x) = 2(3) + 2 = 8 f(x) = x^2 - 1 f(8) = 64 - 1 = 63 f(g(3)) = 4(9) + 8(3) + 3 = 63 ...
*September 7, 2015*

**math**

did you mean f(x) and g(x) to be the same and = x ?? in that case y = x is the equation for both and the inverse of y = x is indeed y = x
*September 7, 2015*

**math**

1x is the same as x (f∘g)(x) = f(g(x) ) = f(x) = x
*September 7, 2015*

**maths**

number present: x number absent : 28-x x = 28-x + 6 2x = 34 x = 17 so present = 17, absent = 11 check: were there 6 more present than absent? YES
*September 7, 2015*

**pre cal**

Have to make an assumption like I had to yesterday: (2 x^-4 y^-1)(2 y^4 z^-1)^-2/ (2yx^3 z^0) = 4x^0 y^-1 z^-1/(2yx^3) , since z^0=1 = 4(1/y)(1/z)(1/(2yx^3) = 4/(x^3 y^2 z) or = 4 x^-3 y^-2 z^-1
*September 7, 2015*

**Math**

We know: (2ab + 5cd)^2 = 4a^2 + 25c^2d^2 + 20abcd plug in the values given, and finish it
*September 7, 2015*

**problem solving**

depends what you mean by "unusual" prob that 1 will fail = C(2,1)(.19)(.81) = .3078 prob that 2 will fail = ...... you try it, let me know how you did it
*September 7, 2015*

**alGEBRA 1**

Writeacher's answer is correct. All you have to do is work it out.
*September 7, 2015*

**probability**

prob no ace = 1 - 4/52 = 12/13 1. so we don't want (no ace, no ace) prob of stated event = 1 - (12/13)^2 = 25/169 2. could be SS, CC, HH, or DD prob(spade, spade) = (4/52)^2 = 1/169 same for each of the others, so prob of stated event = 4/169 3. prob(no ace, no ace) = (12/...
*September 7, 2015*

**Math**

number of cats -- c number of parakeets -- 57-c , there were 57 heads and I assumed each animal had only one head. 4c + 2(57-c) = 176 4c + 114 - 2c = 176 etc
*September 7, 2015*

**math**

cost of eraser --- x cents cost of pencil --- x+25 cents 8(x+25) + 10x = 1280 solve for x and state your conclusion
*September 7, 2015*

**Algbra**

number of general --- x number of reserved --- 1285-x 3x + 5(1285-x) = 4545 solve for x and state conclusion
*September 7, 2015*