Algebra

I've been trying to figure out this equation for over an hour but all the answers I get are wrong. The equation is 0.9=-10I^2+6I . The answer is supposed to be 0.3 and it does work out, but I have tried all different ways to solve for I and nothing seems to work. Could someone please help me?

  1. 👍
  2. 👎
  3. 👁
  1. I assume you know how to complete the square
    -10 x^2 + 6 x = 0.9
    x^2 -.6 x = -0.09
    x^2 -.6 x + .09 = -.09+.09 = 0
    (x-.3)^2 = 0
    x = .3 sure enough.

    1. 👍
    2. 👎
  2. x^2 -.6 x = -0.09 or just rearrange and factor

    x^2 - .6 x + 0.09 = 0
    (x-.3)(x-.3) = 0
    x = .3 and x = .3

    1. 👍
    2. 👎
  3. oh, okay, I see what you're doing. I just have one question, though;why is it that when you get rid of the -10, the 6 is affected by it? I would assume that it would be left alone...

    1. 👍
    2. 👎
  4. oh, I forgot to thank you, so thank you very much!

    1. 👍
    2. 👎
  5. oh, that makes it so much easier! Thank you so very much, it all makes sense now! :D

    1. 👍
    2. 👎
  6. Or use quadratic equation
    -10 x^2 + 6 x = 0.9

    -10 x^2 + 6 x -.9 = 0
    a = -10
    b = 6
    c = -.9

    x = [-6 +/- sqrt (36-36) ]/-20
    =-6/-20
    =-3/-10
    = 0.3

    1. 👍
    2. 👎
  7. I divided both sides of the equation - ALL TERMS by -10

    1. 👍
    2. 👎
  8. -10 x^2 + 6 x
    ---------------
    -10

    = x^2 -.6 x

    1. 👍
    2. 👎
  9. oh, no wonder nothing worked out; thanks!

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. MATH

    An airplane is flying in the direction 148° with an airspeed of u = 865 kilometers per hour. Because of the wind, its groundspeed and direction are v = 780 kilometers per hour and 140°, respectively (see figure in the link

  2. Math

    Leo’s Lawn Care charges $72 for the first hour of mowing, plus $45 for each additional hour. Which equation represents this situation? Select two answers. A.c=45+72(h-1) B.c=72+45(h−1) C.c=45−72(h+1) D.c=72+27h E.c=72+45h

  3. pre-algebra

    Figure B is the image of Figure A. Which description explains how Figure A was transformed to create figure B. A. Figure A was Reflected across a horizontal line of reflection to create Figure B. B. Figure A was rotated 180 °

  4. Algebra

    A sequence is defined recursively by the following rules: f(1)=3 f(n+1)=2⋅f(n)−1 Which of the following statements is true about the sequence? Select all that apply. f(5)=33 f(3)=10 f(4)=18 f(6)=66 f(2)=5 I cannot seem to

  1. Mathematics

    Can someone check my answers? 1. For the data in the table, does y vary directly with X? If it does write an equation for the direct variation.(X,y) (8,11) (16,22) (24,33) Yes y=2.75x Yes y=0.6875x*** Yes y=1.375x No y does not

  2. Mathematics

    2. Write an equation to represent the statement: "The product of a number and five plus two is equal to 100." (1 point) A. 5 - x - 2 = 100 B. 5(x - 2)=100 C. 5 x + 2 = 100 D. 5 - 2 x = 100 3. Solve using mental math. (1 point) 5 x

  3. Math

    1.5gal/min=?qt/h Help!!!! First thing you need to do is figure out how many gallons an hour it is. Since there are 60 minutes in an hour and it's going at 1.5 gallons a minute, we can multiply 1.5 * 60. That's 90 gallons per hour.

  4. Math

    Can anyone help me? 1.Sara works in an ice cream shop. The table shows the number of hours she worked during each of the past four weeks and the amount she earned each week. Time Worked (hours) Amount Earned (dollars) (15) 127.50

  1. math

    Tariq is a mechanic. He charges his customers by the hour. The first hour of service costs $122. The second hour of service costs $171.99. The third hour of service costs $221.98. Write an equation in the form of y=c +d (x -1) to

  2. math

    After being exposed to an electromagnetic shrinking machine, Joe shrank a total of 120 centimeters over 1.2 seconds. His height decreased by the same amount each second. Joe wants to figure out how much his height changed each

  3. Math

    1. Which ordered pair is a solution of the equation y = −11x + 4? a. (0, -7) b. (-1, -7) c. (1, -7) d. (2, 26) MY ANSWER: C Because (X,Y) so -11x = -11 * 1 = -11 -11 + 4 = -7 2. A plumber charges $65 per hour to fix a leak. What

  4. Algebra

    Each summer, Gina picks blueberries at a local berry farm. She can pick 4 pounds of blueberries each hour. Gina is paid $0.65 per pound of berries that she picks. How much does Gina make per hour? $4.04 per hour $9.57 per hour

You can view more similar questions or ask a new question.