# Posts by Reiny

Total # Posts: 39,974

**Math**

Info: loonie - A $1 Canadian coin, showing a loon toonie - A $2 Canadian coin l+t = 45 ---> l = 45-t 1(45-t) + 2t = 67 45 - t + 2t = 67 continue

**math**

decrease = 15400-12950 = ... percent decrease = 100*decrease/15400 =

**Math**

what is 100*620/900 ?

**math**

now: Victoria --- x years old Devante ----- x+2 5 years from now: Victoria ---- x+5 Devante ----- x+7 solve for x, sub back into definitions x+5 + x+7 = 82

**Marh**

length --- 5x m width ----- 3x m Area = 15x^2 m^2 15x^2 *.84 = 624.75 solve for x, and from there find the length and width. Perimeter = 2length + 2 width = 10x + 6x = 16x cost of fencing = 4(16x) = 64x = .....

**math**

What problem?

**math**

the new line is parallel, so it must differ only by the constant. new line: y = x + b sub in (-7,1) to find b, then rewrite my equation

**math .**

#2 is correct #1 , your choice: "it starts with four ..." , really? Are you just guessing?

**Pre-Calc**

to find the inverse of a function, rewrite it in the form y = ..... interchange the x and y variable, then solve this new equation for y so y = 2x^3 + 1 inverse: x = 2y^3 + 1 2y^3 = x - 1 y^3 = (x - 1)/2 y = ( (x-1)/2 )^(1/3) check with a given point, in original let x = 3 , y...

**Math**

A container measuring 10 cm by 10 cm by 10 cm contains 1 L of water See if you can take it from there ?

**Math**

There are only a few of them. I am sure that in the time you took to post your question, you could have studied and learned at least 3 of them.

**Math**

Just noticed that Steve had already answered this question for you. https://www.jiskha.com/display.cgi?id=1507175220 Why did you re-post it ??

**Math**

What is the Least Common Multiple (LCM) of 6 and 8 ?

**Finance**

You can only compare "monies" if they are in the same "time" on your time-line. I would use the present as the reference point. Present Value of option I is $8400 (Clearly if you just paid them 8400, it's all done, right? PV of option II , i = .09/12...

**statistics**

draw a table of 6 rows and 6 columns, with the entries being the sums of the row and column count e.g. /// 1 2 3 4 5 6 1 ..2 3 4 5 6 7 2 ..3 4 5 6 7 8 3 .. 4 .. 5 ..6 7 8 9 10 11 6 Now count the "sums" that related to your question and you should be able to answer ...

**Algebra: Please Help.**

16y^3+48y^2=-36y First divide each term by 4 and "move" the term from the right side to the left 4y^3 + 12y^2 + 9y factor out a y y(4y^2 + 12y + 9) = 0 I see a perfect square y(2y + 3)^2 = 0 y = 0 or 2y+3 = 0 y = 0 or y = -3/2

**Algebra: Please Help.**

we are still ok with 10x^2+5x+5=0 now divide each term by 5 2x^2 + x + 1 = 0 doesn't factor, so we have to use the formula x = (-1 ± ?(1 - 4(2)(1)) )/4 = (-1 ± ?-7)/4 = (-1 ± ?7 i)/4 , a pair of complex numbers

**Math**

Assuming the payments are made at the end of a period to match the standard formulas outstanding balance = 10000(1.0058333...)^6 - 349.72( 1.0085333..^6 - 1)/.00853333... = .....

**Math**

at the 2.5 year mark i = .078/12 = .... n = 2.5(12) = 30 follow the same steps I just showed you in your next post

**Calculus 1**

at a time of t seconds ... let the radius of the circular water level be r let the height of the water be h 12/9 = h/r 12r = 9h 4r = 3h ----> r = 3h/4 V = (1/3)? r^2 h = (1/3)? (9h^2/4)(h) = (3/4)? h^3 dV/dt = (9/4) h^2 dh/dt 5 = (9/4)? (4) dh/dt solve for dh/dt

**Math plz help**

#2 | y+4| <1 Use your definition: y+4 < 1 AND -y-4 < 1 y < -3 AND -y < 5 y < -3 AND y > -5 or as they wrote it, -5 < y < -3

**Math plz help**

The last one is correct, the first two are wrong. Show me your steps so I can tell where you are going wrong.

**Math plz help**

I don't see your choices, so how can we check?

**Math**

What is the change in temperature? note, it will be negative, (dropping) What is the change in time from 1:00 pm to 9:00 pm average change in temperature per hour = total change in temperature / change in time = ...... degrees/hour

**Math**

10x + y= 2xy-9 y - 2xy = -9 - 10x y(1 - 2x) = -9-10x y = (-9 - 10x)/(1 - 2x) or y = ( 9+10x)/(2x-1) pick any x you want, evaluate the y. You can get as many values of x and y as you want. The only value of x you can't choose is x = 1/2 , since for that value you would be ...

**Math**

Why did you re-post the question after it has been answered??? https://www.jiskha.com/display.cgi?id=1507039066

**Math**

Nothing to solve, just multiply the two numbers. (Do 3 x 67, you should be able to do that in your head, then move the decimal 3 places to the left.) Of course you could also use your calculator.

**Math**

The way you typed it : 5^x + 2•5^x+1 = 3*5^x + 1 it does not factor over the rational numbers Secondly you did not say what type of number x is, let's assume x is a whole number, that is x = 0, 1, 2, 3, ... if you meant: 5^x + 2*5^(x+1) = 5^x( 1 + 2(5^1) ) = 5^x ( 11...

**Math**

first term --- a second term ---- ar a - ar = 2 a(1-r) = 2 sum to infinity = 15 a/(1-r) = 15 [a(1-r)][a/(1-r)] = 2(15) a^2 = 30 a = ± ?30 from a = ar+2 ?30 = ?30r + 2 r = (?30 - 2)/?30 = 1 - 2/?30 so we have ?30, ?30 + 2 , .... sum(5) = a (r^5 - 1)/(r-1) = .... = ..... ...

**math**

when it hits the ground, h = 0 0 = -4.9x^2 + 21.3x 4.9x^2 - 21.3x = 0 x(4.9x - 21.3) = 0 x = 0 , which corresponds to the moment she kicks the ball or x = 21.3/4.9 = appr 4.4 seconds

**Math**

I guess you could form columns for "n" and "left side" n ... LS 0 3 1 9 2 15 --- getting too big, looking for 2 on RS -1 -3 ---- too low, so n is between 0 and -1 1/2 6 ---- too high -1/2 -3 --- too low so between 0 and -1/2 -1/4 3/2 ----- too low so ...

**math**

notice that each new term is -3 times its previous, or tn = -3t(n-1) so we have -4, 12, -36, 108, -324

**Algenra 1**

both correct

**math**

This is the same type as your other post. Only this time you don't add anybody not belonging to either set.

**Calculus**

Do you actually expect somebody to do this assignment for you?

**MATH**

No, the 5 that do both are counted in the 16 geography students, AND the 18 chemistry students, so you are counting them twice number of students = 16+18 - 5 + 3 = .... make a Venn diagram to see.

**Math**

10(x+27) ? 26

**Math**

You will have to count the number of days from Feb 12 to June 23, I will leave that up to you and label it 'days' in I = PRT, your I = 40, R = ??, T = days/365 , P = 2000 40 = 2000(R)(days/365) R = 40(365)/(2000(days)) = your R will be a decimal, I will assume you know...

**pre-calculus math**

a zero of 3 gives us a factor of (x-3) complex zeros always come in conjugate pairs, so if -3-2i is one of them, -3+2i must be another. factors are (x - (-3-2i)) and (x - (-3+2i)) or (x + 3 + 2i) and (x + 3 - 2i) multiply the last two to get a quadratic factor (......) your f(...

**Math**

Thanks Steve, how sloppy of me

**Math**

amount of the 1% stuff to be added ---- x ounces .1x + .4(100) = .16(x + 100) solve for x

**Algebra**

f(2) = 21 , you had that f(a) = 6a^2 - 3 all you had to do is find the average rate of change, or more commonly known as the slope average rate of change = (6a^2 - 3 - 21)/(a - 2) = (6a^2 - 24)/(a-2) = 6(a^2 - 4)/(a-2) = 6(a+2)(a-2)/(a-2) = 6(a+2) , a ? 2

**Math**

1.6666666667 is NOT an irrational number. (1.6666666667 = 16666666667/10000000000 , there! I wrote it as a rational number)

**Calculus**

Your equation should have been h = -16t^2 - 6t + 130 When it hits the ground, h = 0 so, 16t^2 + 6t - 130 = 0 I would use the quadratic equation formula to solve for t (to be able to handle this topic, you MUST know that formula) make sure to reject any negative value of t.

**Math**

PV = 30,000 + 30,000( 1 - 1.0593^-12)/.0593 = ....

**alg**

y = 3x - 1 for (2,5) LS = 5 RS = 3(2) - 1 = 5

**Algebra**

I just googled : graph of a quadratic function, and guess what ? replace "quadratic" with the other two words

**Advanced Algebra**

I agree, but then pay this off as quickly as possible with such a high interest rate. Notice the payment of $25 wouldn't even pay the interest. (first months interest after introductory period = 1800(.2399)(1/12) = $35.99

**1 Out Of 100 Math Trick HELP PLEASE!!!**

1. Choose a number between 1 and 100. ------> x 2. Multiply the number by 5. -------> 5x 3. Add 15 to the number. -------> 5x+15 4. Divide the number by 5. ------> x+3 5. Subtract the original number. ------> 3 try it with any number: 1. ----- 12 2. ------ 60 3...

**Pre-calc**

Use brackets to write the fractions, such as 1/(2x) + 6/2 , <---- that was a guess, I can't tell what you meant

**Pre-calc**

I will assume that these are the zeros or the solutions to your function = 0 if 3-i is a zero, then 3+i is a zero, since complex solutions always appear in conjugate pairs sum of those roots = 6 product of those roots = 9 - i^2 = 10 so the quadratic producing those two complex...

**Algebra**

your formula is interpreted this way f(3) = f(2) + f(1) f(4) = f(3) + f(2) f(5) = f(4) + f(3) etc so f(3) = 3 + 2 = 5 f(4) = ....... notice we already eliminated b) continue .... btw, this is a famous sequence called the Fibonacci sequence, one of my favourite topics in Math.

**Math**

How did you possible get those answers ???

**Algebra**

What problem? Are you switching names ??

**Algebra**

No How did you get that ????

**Math**

remember , Perimeter = 2 x width + 2 x length area = length x width Perimeter = 2(5x-4) + 2(5x) = .... area = 5x(5x-4) = ... in each case simplify my expression

**Pre-Calculus**

To prove an identity, we usually start with one side and using basic identities show that it is equal to the other side LS = cosx - sex = cosx - 1/cosx = (cos^2 x - 1)/cosx = - sin^2 x / cosx = -sinx(sinx/cosx) = -sinx tanx = RS

**Math**

Didn't you want to make at least $200 ? So it should be 15h ? 200 h ? 40/3 , not less than like you had However, your conclusion that the painter must work a minimum of 13 and 1/3 hours to earn at least $200, is correct

**Math**

correct,

**Algebra 2**

depends on the transformation. e.g. suppose we have f: (x,y) ----> (x,-y) , a reflection in the x-axis , and g: (x,y) ---> (-x,-y) , a reflection in the origin if we do fg (x,y) ---> (x,-y) ---> (-x,y) and if we do gf (x,y) = (-x,-y) ---> (-x,y) , we get the ...

**math**

explain the meaning of 127nine

**algebra**

| 4x - 5 | > 4 4x - 5 > 4 OR -4x + 5 > 4 4x > 9 or -4x > -1 x > 9/4 or x < 1/4 change into the notation you learned and graph on a number line

**algebra 2**

6x-8 = 4 or -6x+8 = 4 6x = 12 or -6x = -4 x = 2 or x = 2/3

**algebra**

follow the same steps and procedure as in https://www.jiskha.com/display.cgi?id=1506548306 except use AND between the two inequations

**algebra 2**

width --- x length --- 2x perimeter = 2width + 2 lengths = 54 continue

**algebra**

Both conditions are referenced in terms of nickels, so let the number of nickels be x number of dimes = x+1 number of pennies = x+6 Value equation: 5x + 10(x+1) + x+6 = 480 continue ....

**Algebra 2 A**

correct make sure your equation is 26.00+3.25x=24.00+3.50x

**maths**

Ummmhh, if you are half as old as your sister, wouldn't your sister be twice as old?? . I defined it the way I did to avoid fractions. What does 6(x-20) mean? Does it not say 6 times (the son's age) ?? 2x-20 = 6(x-20) 2x-20 = 6x - 120 -4x = -100 x = 25 So the son is ...

**maths**

So the father is now twice as old as his son son's age ---- x father's age ---- 2x Twenty years ago : son's age = x-20 father's age = 2x-20 2x-20 = 6(x-20) solve for x, etc

**math**

first of all , you have a typo in g(x)=x^2=7x I think you meant: g(x)=x^2+7x , since the + and the = are on the same key you are given that g(x) = x^2 + 7x so you want g(3). As Philip stated, wherever you had an x , now put in a 3 g(3) = 3^2 + 7(3) = 9 + 21 = 90 so since f(x...

**College Algebra: Please Help Me. Thanks.**

f(x)=4x^2+3x+5 and g(x)=3x^2+2x+2 I will do A and C, you do the rest a) (f+g)----> 7x^2 + 5x + 7 (f+g)(3) = 7(3)^2 + 5(3) + 7 = 63 + 15 + 7 = 85 c) (f-g)(x) = 4x^2+3x+5 - (3x^2+2x+2) = x^2 + x + 3

**Math**

a) h = 8 + 6t 6t = h-8 t = (h-8)/6 c) when t = 6 h = 8 + 6(6) = .... d) when h = 29 29 = 8 + 6t 21 = 6t t = 21/6 = 3.5 it would take 3.5 months

**PRE-CALC**

you are given that x = i is a solution Complex roots, just like irrational roots, always come in conjugate pairs, so x = -i is another solution so you know (x+i) and (x-i) are factors (x+1)(x-1) = x^2 + 1 which means x^2 + 1 is factor of your given polynomial now do a long ...

**8th grade Math Connections Academy**

#5 25 is a perfect square ---- 5^2 = 25 , but 27 is a perfect cube --- 3^3 = 27 #6 is incorrect ?9 - 7 = 3-7 = -4, which is an integer Whole numbers are positive integers I agree with the others.

**Math**

24.4 trillion = 24,400,000,000,000 cost per person = 24,400,000,000,000/325,000,000 = 24,400,000/325 = $62,769 At $62 it could be paid off in 1 year by everybody chipping in a bit, unfortunately .....

**Math**

number dogs = 135(.365)(1.6) = appr 78.8 million dogs

**math**

-8y+3(g+h) - -5y-4(g+h) = -8y + 3g + 3h + 5y - 4g - 4h = ..... btw, - - 5 is considered "poor mathematical form"

**Maths**

I drew a horizontal flight path 400 m above the ground. On that path, I labeled the first position of the plane as A and the 2nd position as B, and the location of Melbourne on the ground as M I also labeled C on the flight path as the point directly above M. Let the speed of ...

**math**

3150 = 9*25*14 you take it from here

**9th Grade Math**

yes

**9th Grade Math**

none are correct A typical equation of a straight line, other than vertical or horizontal lines, need an x and a y variable. I will do one of them , say #4, you do the others slope of line = (-10-2)/(15-5) = -12/10 = -6/5 using the point (5,2), y - 2 = (-6/5)(x-5) multiply ...

**Calculus**

Let the vertex on the line 3x + 4y = 12 be (x,y) then y = (12-3x)/4 = 3- 3x/4 area = xy = x(3 - 3x/4) = 3x - 3x^2 /4 d(area)/dx = 3 - (3/2)x = 0 for a max of area (3/2)x = 3 3x = 6 x = 2 , y = 3 - 6/4 = 3/2 max area = xy = 2(3/2) = 3 units^2

**math Please help!!**

look at your list of properties, which pattern do you see?

**math Please help!!**

one has square brackets around it, and the other one doesn't. I would consider both to be -3

**algebra**

each of the equal angles ---- x third angle = 2x - 4 so : x + x + 2x-4 = 180 continue

**Algebra**

now: son's age --- x man's age --- 3x 5 years ago: son's age = x-5 man's age = 3x-5 3x-5 = 4(x-5) solve and the mystery will be unravelled.

**math**

just solve the two equations. I would use y = 20-x from the first and sub it into the 2nd let me know what you get

**math**

Here is just one such worksheet http://www.bearsdenacademy.e-dunbarton.sch.uk/_includes/attachments/P1283/Unit2_TrigonometricEquations.pdf That should keep you busy for a while. Try the questions before looking at the solutions.

**math**

Your first source would be your textbook. Perhaps your teacher gave you a handout of such equations. You can always google "trig equations" or "trig equations worksheet" There would be an infinite number of such equations.

**maths**

time in car ---- t hrs time on motorcycle --- 1 - t hrs 30t + 18(1 - t) = 22 solve for t, sub into 30t to get the distance in km

**Math**

width --- w length --- 3w 2(w+3w) = 96 4w = 48 w = 12 m or 1200 cm 3w = 36 m or 3600 cm area of flower bed = 1200(3600) cm^2 area of rectangle including path = (1280)(3680) cm^2 area of walkway = the difference or 390400 cm^2 volume of concrete needed for walk = 390400(15) cm^...

**algebra**

5x - 3y = 0 5x = 3y or 3y = 5x y = (5/3)x , which is in the form of y = mx, a direct variation.

**Math**

The areas of two similar figures area proportional to the square of their corresponding sides, so w^2/18^2 = 52/117 w^2 = 144 w = ?144 = 12

**Physics/Math**

You must be studying vectors in 3-D and cos ?, cos ?, and cos ? must be the direction cosines of a vector <a, b, c> you will recall that cos ? = a/?(a^2 + b^2 + c^2) cos ? = b/?(a^2 + b^2 + c^2) cos ? = c/?(a^2 + b^2 + c^2) Here is a great youtube which uses a specific ...

**maths**

What happened to the 100 ml that were split ? If they were given as part of the share , why not just do 2500 ml ÷ 4 = 625 ml per child or 100 ml ÷4 = 25 ml remaining 2400 ml ÷ 4 = 600 ml, and of course 600 ml + 25 ml = 625 ml , same as above

**Math**

Where are points a and b on the pond? What is a mosese ?

**Further maths**

Let x be the number who passed both. x + 31-x + 29-x + 3 = 50 -x = -13 x = 13 number who passed Chemistry only = 31-x = 31-13 = 18

**Math**

In most languages, there are special words for very common numerical values, as well as mathematical concepts e.g. almost every language has a special word for 12 besides the numerical name. That is, in English we use "dozen" meaning 12, in German "Dutzend"...

**math**

translating your conditions: W = k * w* h^2 / l given: w = 3in, h = 4in, l = 6 ft or 72 in , W = 28 tons 28 = k(3)(16)/72 k = 42 W = 42 * w* h^2 / l plugging in the second case: W = 42(5)(16)/240 = 14 tons

**Algebra 2**

6|6-4x|=8x+4 divide by 6 |6-4x|=(8x+4)/6 ---- I wanted to isolate the absolute value expression 6-4x = (8x+4)/6 OR 6-4x = -(8x+4)/6 36-24x = 8x+4 or 36-24x = -8x - 4 -32x = -32 or -16x = -40 x = 1 or x = 40/16 = 5/2 I will leave it up to you to verify my answers