# Posts by Steve

Total # Posts: 49,504

**Math - Calculus**

I hope it was not you who posted this earlier, where I explained it all. http://www.jiskha.com/display.cgi?id=1489049850

*March 9, 2017*

**Geometry**

Note that each value is multiplied by 3.

*March 9, 2017*

**Math**

well, yes. The next step is to use their sum to actually find x's value: 8x=80 x=10 Now, you can get the two numbers, once you know x.

*March 9, 2017*

**Math**

the numbers are 3x and 5x. so, add them up, solve for x, and ...

*March 9, 2017*

**math**

charity: 5% = 15 saves: 2/5 = 40% = 120 remainder: 175 = 55%

*March 9, 2017*

**pre calc**

It is not (D) because f(x) has a maximum at 35.12 That means that f(x) fails the horizontal line test on the interval (30.24,40), so it is not invertible there.

*March 9, 2017*

**Science**

take just a moment to think about this. Surely you can tell which is the only possible choice. The sun is just a huge, hot ball of gas ...

*March 9, 2017*

**Math**

perpendicular lines have slopes whose product is -1. So, you need -k/6 * -3/2 = -1 k = -4 The 2nd line has slope -3/2. So, its angle of inclination is arctan(-3/2) = -56.3°

*March 9, 2017*

**Math Calculus**

You know what parabolas look like. (x-1)(x-3) is negative between the roots, so this graph has a bump in the middle. Since the axis of symmetry is x=2, f(-1) = f(5) = 8 f(2) = 1 so, the max value is 8 and the minima are 0. f(2) is also a local max, since it is the vertex of ...

*March 9, 2017*

**Math - extreme values**

The critical points are where f' is zero or undefined. It is never undefined. So, remembering your Algebra I, f' = 0 when x=0 or cosx=0: x = odd multiples of ?/2 x=0 is not in the domain, so the only critical points are at x = -?/2 and -3?/2. Naturally, the extreme ...

*March 9, 2017*

**Physics 2017**

measure the diameter of the wire. Then, knowing the weight of the coil, and subtracting the weight of the core, the remaining weight is purely the wire. Now divide the mass of wire by the density to get the volume of wire. Divide that by the cross-section area to get the length.

*March 9, 2017*

**science**

take a look at Snell's Law

*March 8, 2017*

**math**

5C3 if order does not matter

*March 8, 2017*

**Math**

20000*1.05^20 - 15000*1.05^20 = (20000-15000)*1.05^20 = 5000 * 1.05^20 or, consider that the difference is just the amount f interest earned by the extra $5000 that Lisa deposited. 5000*1.05^20 Note that the growth factor is 1.05, not just .05, since .05 gets smaller and ...

*March 8, 2017*

**math**

(x+2)(x-7) <= 0

*March 8, 2017*

**math**

clearly you need roots at -2,1,4 Since p < 0 on the first interval, it must be >0 when x < -2. So, the leading coefficient must be negative, giving us p(x) = -a(x+2)(x-1)(x-4) where a is any positive value. See the graph for a=1 here: http://www.wolframalpha.com/input...

*March 8, 2017*

**Algebra2**

my answer is: x^2/9+y^2/4=1 Sorry about that!

*March 8, 2017*

**Algebra2**

Write an equation of an ellipse in standard form with center at the origin and with the given vertex and co-vertex vertex at (-3,0) and co-vertex at (0.2)

*March 8, 2017*

**Algebra2**

Thank you

*March 8, 2017*

**Algebra2**

I forgot my answer: (x+2)^2 = 4(y-5)

*March 8, 2017*

**Algebra2**

What is an equation of a parabola with the given vertex and focus? vertex(-2,5) focus(-2,6)

*March 8, 2017*

**Probability: Combinations**

6C2 = 6*5/2 = 15

*March 8, 2017*

**Algebra2**

Write an equation of a parabola with a vertex at the origin and a directrix at y=-5. my answer is focus 6,0, directrix =-6

*March 8, 2017*

**Algebra2**

thank you

*March 8, 2017*

**Algebra2**

-3x^2+12y^=84 What are the domain and range My answer domain: all real numbers range: y (less than -) -sqrt7 or sqrt7

*March 8, 2017*

**Algebra2**

What are it's line of symmetry? 4x^2+y^2=9 my answer is it has 2 lines of symmetry, the x and y axis

*March 8, 2017*

**maths**

If there are e erasers, p pencils, and q pens, we have 2e+4p = 240 6e+p+2q = 395 e+p+4q = 415 If A is the matrix of coefficients, then A^-1 = 1/84 (-2 16 -8) (22 -8 4) (-5 -2 22) Then you have (e p q) = (30 45 85) See here: http://www.wolframalpha.com/input/?i=inverse+%7B%7B2,...

*March 8, 2017*

**Science**

No ideas? Surely you have a calculator.

*March 8, 2017*

**Algebra2**

thank you

*March 8, 2017*

**Algebra2**

4x^2+4y^2=64. what are the domain and range? my answer is domain;all real numbers range;-4<=4<=4

*March 8, 2017*

**Math c2**

well, 3?(x^2+1) = ?(9x^2+9) = ?(3x)^2 + 9) So, it looks like a horizontal compression by a factor of 3.

*March 8, 2017*

**Math**

well, for usage over 50 therms, the bill for x therms is y = 67.65 + 1.1917(x-50) So, plug in your y values and solve for the x values.

*March 8, 2017*

**maths**

well, where is x^2-x-6 = 0? You cannot divide by zero, and the square root is not real for negative values, so ... the domain is x values where x^2-x-6 is positive.

*March 8, 2017*

**algebra**

Think about it like this. With 5 types of seeds, there are 5 choices for the 1st flower. For the 2nd flower, there are only 4 choices. For the 3rd flower there are 3 choices. Now you know how many ways the 3 flowers can be planted. But if all you want is the combinations, the ...

*March 8, 2017*

**math**

4x^2+19x-5 = (4x-1)(x+5) The roots (places where the graph crosses the x-axis) are -5 and 1/4 So, where do you think the value is negative?

*March 8, 2017*

**Precaculus**

(0.1 cm^3)/(4?/3 * (5*10^-3 cm)^3) = 0.1/(5.24*10^-7) = 190986 cells V(t) = 0.1 * 2^(t/20)

*March 8, 2017*

**maths**

you know the circumference of a circle is ?d, right? Think of the circle as a round piece of string. Cut it and lay it out straight. That's how far the wheel travels in one complete turn.

*March 8, 2017*

**Math**

sum means add (product means multiply) same mistake. "/" means divide -8n ok your answers are ok if you meant x+(-3) times means multiply. You really seem to have a problem here... and yet you got y-5 correct.

*March 8, 2017*

**Math**

2(80+x) = 410 area = 80x

*March 8, 2017*

**Math**

well, he spent 1/4 + 1/3 + 1/5 = 47/60

*March 8, 2017*

**English**

clearly, neither. It just mentions shoes of no specific kind.

*March 8, 2017*

**Math**

5P2 * 12P4 = ?

*March 8, 2017*

**Algebra 2**

or, for a more condensed presentation, type in your coefficients here and see all the details. http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

*March 8, 2017*

**Math**

they must be flying in the same vertical plane, if they are traveling with an angle relative to the horizontal ... Also, I suspect A's speed is 100?3 m/s, not mi/s. Using the law of cosines, 500^2 + (100?3 t)^2 - 2(500)(100?3 t)(?3/2) = (100?3 t)^2 They will crash in 5/3 ...

*March 8, 2017*

**science**

well, how many moles of Fe2O3 in 108kg? Now balance the equation: Fe2O3 + 3CO -> 2Fe + 3CO2 Now you can see how much CO is used.

*March 8, 2017*

**Math**

well, 27+28 = 55

*March 7, 2017*

**calculus**

the 3-foot radius and 2-foot depth means that y = 2/9 x^2 The arc length of the parabola is ?[0,3] ?(1+y'^2) dx Now just rotate that, remembering that the circumference of a circle is 2?r.

*March 7, 2017*

**Math**

well, what about zero factors?

*March 7, 2017*

**math**

2(w + w+9) = 110

*March 7, 2017*

**ATI TEAS 6 practice**

as for the -20x+20, 5(x-2)^2 = 5(x^2-4x+4) = 5x^2-20x+20

*March 7, 2017*

**ATI TEAS 6 practice**

not much factoring here. 5(x-2)^2 = 125 (x-2)^2 = 25 x-2 = ±5 x-2 = +5: x = 7 x-2 = -5: x = -3

*March 7, 2017*

**Math age problem/ Solving Multi step Equations**

a = 2m-15 a+m = 12 ...

*March 7, 2017*

**Calculus Answer Check**

good numbers, but what about [0,10]?

*March 7, 2017*

**Math**

*sigh* 7 5/16 + 3 3/4 = 7 5/16 + 3 12/16 = 7+3 + 5/16+12/16 = 10 17/16 = 11 1/16 clearly you need to review operations with fractions.

*March 7, 2017*

**Math**

7 5/16 + 3 3/4 place fractions over a common denominator and add.

*March 7, 2017*

**Hot math questions**

not if S is the number of shoes in S/2 pairs ...

*March 7, 2017*

**Maths trigonometry**

trés simple -- x = Sin Alfa / (335sin59) now just get out your calculator. sure looks like a Law of Sines problem to me.

*March 7, 2017*

**FUR. MATHS**

judging from the student's alleged name, we want something like (f?g)(x) = f(g) = 2g-1 = 2(5-2x)-1 = ...

*March 7, 2017*

**Algebra math 150**

I guess it depends on what you are trying to do...

*March 7, 2017*

**maths**

The range of f^-1(x) is (-9/4,?) x = (1-5y)/(2y) 2xy = 1-5y y = 1/(2x+5) so, f(x) = 1/(2x+5) domain is (-9/4,?)

*March 7, 2017*

**Math**

?[1,5] (ln2x - lnx) dx = ?[1,5] ln2+lnx-lnx dx = ?[1,5] ln2 dx = 4ln2

*March 7, 2017*

**Geometry**

Hard to say what you did wrong, since you didn't show your work. First, learn to use parentheses: 9/(4x-2) = 12/(3x+2) 9(3x+2) = 12(4x-2) 27x+18 = 48x-24 21x = 42 x = 2

*March 7, 2017*

**Long Division**

SEE ALL THE DETAILS HERE: http://calc101.com/webMathematica/long-divide.jsp

*March 7, 2017*

**math**

if you say so. Hard to tell, since you don't say when you leave...

*March 7, 2017*

**calculus**

Each shell has thickness dy and height x = 2/y So, the volume v is v = ?[2,4] 2?rh = ?[2,4] 2?y(2/y) dy = ?[2,4] 4? dy = 8? As a check, you can use discs, getting v = ?(4^2-2^2)(1/2) + ?[1/2,1] ?(R^2-r^2) dx where R=y and r=2 v = 6? + ?[1/2,1] ?((2/x)^2-2^2) dx v = 6?+2? = 8?

*March 7, 2017*

**math question**

so, move left-right 1 and up-down 2 or left-right 2 and up-down 1. One such point will be (1+1,2+2) = (2,4) I think you will find 8 such points, not 4.

*March 7, 2017*

**maths**

I can't figure out what circle (O, OP ) is passing from A means.

*March 7, 2017*

**maths**

I assume that "circle (P,12)" means a circle with center at P and radius 12. If so, then the distance between the circles is 25-12-5 = 8 Draw the diagram. Label O the point midway between the circles. Then we have two right triangles PAO and QBO PO=16 and PA=12 QO=9 ...

*March 7, 2017*

**Geometry**

surely you know that the circumference of the semi-circle is 300? so, add that to the 3 straight sides,

*March 7, 2017*

**math NEED HELP ASAP**

.60x + 1.00(120-x) = .70*120

*March 6, 2017*

**Calculus**

either 5+2/x < 1 or -(5+2/x) < 1 In the first case, x is in (-1/2,0) In the 2nd case, x>0 or x < -1/3 . . .

*March 6, 2017*

**Math**

so, just solve for d when -0.02d^2+2.6d-66.5 = 0

*March 6, 2017*

**Math**

#1 y = (3/4)x+b 7 = (3/4)*4+b b=4 so, y = (3/4)x+4 Clearly (0,0) does not satisfy that equation #2 x/y can be zero if x=0 Only y cannot be zero. #3 ok #4 volume is always in cubic units. Area is square units. #5 85+92+80+90+x = 5*89 x = 98 How could you possibly believe such a...

*March 6, 2017*

**math**

do the () first 10-7=3 3 squared=9 4 times 9 =36 36 times 7 =252 252+4=256

*March 6, 2017*

**math**

subtract the 25 from 14

*March 6, 2017*

**math**

15+19=34 34-6=28 28/2=14 14-25=negative 11

*March 6, 2017*

**Algebra2**

thank you very much

*March 6, 2017*

**Algebra2**

find a quadratic function in standard form for each set of points. (-1,2),(0,1),(1,-4)

*March 6, 2017*

**mathemadics**

come on. Take a stick and break it into thirds. How many pieces are there?

*March 6, 2017*

**math**

at 3 m/s, time t: 3t time t+1: 3(t+1) = 3t+3

*March 6, 2017*

**Math**

coconut: (3/5)(1/3) = 1/5 angel: (2/5)(1/6) = 1/15 assuming no cakes are coconut ... If all the cakes are either coconut or angel food, then coconut: (3/5)(1/3) + (2/5)(5/6) = 8/15

*March 6, 2017*

**Algebra**

how about 7*2*9 ?

*March 6, 2017*

**Algebra**

2 legs per animal yields 26 legs There are 6 extra legs, so what does that say? Think about what happens when you replace a chicken with a sheep.

*March 6, 2017*

**Calculus**

Too bad you didn't show your work... f' = 1 + 2cosx f'=0 when cosx = -1/2 x = 2?/3, 4?/3 f" = -2sinx f"(2?/3) < 0, so that is a maximum f"(4?/3) > 0, so that is a minimum See the graph at http://www.wolframalpha.com/input/?i=x%2B2sinx,+for+x+%...

*March 6, 2017*

**Math**

m = kh now plug in your numbers

*March 6, 2017*

**Math**

a:b = 3:8 b:c = 1:6 = 8:48 a:b:c = 3:8:48 a:c = 3:48 = 1:16

*March 6, 2017*

**Math**

no idea what the shaded region is.

*March 6, 2017*

**Algebra**

plot each line and the solution is where they intersect.

*March 6, 2017*

**math 73**

add up the amount of fat in the milk and cream. It must equal the amount in the mix. If there are x gallons of cream, then the rest (20-x) is milk. So, .22x + .02(20-x) = .04(20)

*March 6, 2017*

**Geometry**

2(w+78) = 260

*March 6, 2017*

**maths curve need help**

First step: draw the graphs! They intersect at (0,0) and (1,1). You want to rotate a small lens-shaped area. To find the volume, you can do two methods. Think of the volume as a stack of discs with holes (washers). The holes are there because a slice of area is rotated around ...

*March 6, 2017*

**Math**

#1 #2 are ok the volumes are in the cube of the linear ratio. So, v' = (10/15)^3 v = 8/27 v = 160 This is due to the fact that each dimension scales the same way. In the case of the sphere, replace r by (2/3)r in the formula. Then you get v = 4?/3 r^3 v' = 4?/3 (2/3 r...

*March 6, 2017*

**Algebra2**

a = a1 = 2*1-3 = -1 d = an+1-an = (2(n+1)-3)-(2n-3)) = 2 Now just use your sum formula S10 = 10/2 (2a+9d)

*March 6, 2017*

**Algebra2**

What is the sum of the first 10 terms of the sequence defined by an = 2n - 3?

*March 6, 2017*

**Math**

good start, but 16 years means 32 payments.

*March 6, 2017*

**physics**

recall that the index n is defined by n = c/v

*March 6, 2017*

**Calculus**

I assume a triangular cross-section. So, the width of the water surface when it has a depth of y is y/2. Thus the volume of water of depth y is v = (1/2)(y)(y/2)(8) = 2y^2 dv/dt = 4y dy/dt Now just plug in your numbers

*March 6, 2017*

**math**

same as for any regular n-gon: area = 1/2 perimeter * apothem But it will be very close the the circle.

*March 6, 2017*