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Help me with unsolveable problems?

This is my second go with College Algebra. I am a junior in college going to school on a financial aid program that only covers me a limited number of classes so I cannot keep re-taking this class. We use a computer program for all homework and the 'help me solve this' button isn't helping. here are the last problems from Chapter 1 that I can't figure out. Someone please solve these for me..

1.) 2x2 - 3x - 35 = 0

x=_______ (smaller value)

x=_______ (larger value) I got -5/2 as smaller value and 7 as larger value.

2.) Use the quadratic formula to solve the equation.

5x(x + 9) = -65

x=_____ (smaller value)

x=______ (larger value) I got -9/2 and -5/2

3.) Change the equation to quadratic form and solve it by the most efficient method.

x − 2 = 8/x (the 8 is 8 over x)

x=_____ (smaller value)

x=_____ (larger value) (even the textbook did not have an example to teach me how)

4.) Change the equation to quadratic form and solve it by the most efficient method.

1/x-1 + 1/x-5 = 3/8

x= _____ (smaller value)

x= ______ (larger value)

5.) Change the equation to quadratic form and solve it by the most efficient method.

29/b - 23 = -22/b+1

x= _____ (smaller value)

x= ______ (larger value)

Thank you so much. If you guys can solve these 5, I will make about a B.

Update:

the 2x2 in number 1 is 2x squared

5 Answers

Relevance
  • QC
    Lv 7
    9 years ago
    Favorite Answer

    To denote powers use ^, i.e. x squared = x^2, x cubed = x^3, etc...

    2x^2 - 3x - 35 = 0

    2x^2 - 10x + 7x - 35 = 0

    2x (x - 5) + 7 (x - 5)

    (2x + 7) (x - 5) = 0

    x = -7/2

    x = 5

    It looks like you got the 2 coefficient in the wrong factor

    -------------------------------

    2.

    5x(x + 9) = -65

    x (x + 9) = -13

    x^2 + 9x + 13 = 0

    x = (-9 ± √(81 - 4(1)(13))) / 2

    x = (-9 ± √(81-52)) / 2

    x = (-9 ± √29) / 2

    Smaller value: (-9 - √29)/2

    Larger value: (-9 + √29)/2

    -------------------------------

    3.

    I'm not exactly sure what sort of example you expected.

    Have you never been showed how to cross-multiply, to get rid of denominators?

    (x - 2) = 8/x

    x (x - 2) = 8

    x^2 - 2x - 8 = 0

    (x + 2) (x - 4) = 0

    x = -2

    x = 4

    -------------------------------

    4.

    This time instead of cross-multiplying, we'll just multiply both sides by least common denominator

    1/(x-1) + 1/(x-5) = 3/8

    Multiply both sides by lcd = 8(x-1)(x-5)

    8(x-1)(x-5)/(x-1) + 8(x-1)(x-5)/(x-5) = 8(x-1)(x-5) * 3/8

    8(x-5) + 8(x-1) = 3(x-1)(x-5)

    8x - 40 + 8x - 8 = 3 (x^2 - 6x + 5)

    16x - 48 = 3x^2 - 18x + 15

    0 = 3x^2 - 18x + 15 - 16x + 48

    3x^2 - 34x + 63 = 0

    3x^2 - 27x - 7x + 63 = 0

    3x (x - 9) - 7 (x - 9) = 0

    (3x - 7) (x - 9) = 0

    x = 7/3

    x = 9

    -------------------------------

    5.

    29/b - 23 = -22/(b+1)

    Multiply both sides by b(b+1)

    29(b+1) - 23b(b+1) = -22b

    29b + 29 - 23b^2 - 23b = -22b

    -23b^2 + 6b + 29 = -22b

    -23b^2 + 28b + 29 = 0

    23b^2 - 28b - 29 = 0

    b = (28 ± √(784 - 4(23)(-29))) / 46

    b = (28 ± √(784 + 2668)) / 46

    b = (28 ± √3452) / 46

    b = (28 ± 2√863) / 46

    b = (14 − √863) / 23

    b = (14 + √863) / 23

    Mαthmφm

  • Jay
    Lv 5
    9 years ago

    1) 2x²-3x-35 = 0

    (2x+7)(x-5) = 0

    x = -7/2 = smaller value, 5 = larger value

    2) 5x(x+9) = -65

    5x²+45x = -65

    5x²+45x+65=0

    x²+9x+13 = 0

    x = (-9±√29)/2 = (-9-√29)/2 = smaller value, (-9+√29)/2 = larger value

    3) x-2 = 8/x

    x(x-2) = 8

    x²-2x-8 = 0

    (x-4)(x+2) = 0

    x = 4 = larger value, -2 = smaller value

    4) 1/(x-1) + 1/(x-5) = 3/8

    [(x-5)+(x-1)]/(x-1)(x-5) = 3/8

    (2x-6)/(x-1)(x-5) = 3/8

    8(2x-6) = 3(x-1)(x-5)

    16x-48 = 3(x²-6x+5)

    16x-48 = 3x²-18x+15

    0 = 3x²-34x+63

    0 = (3x-7)(x-9)

    x = 7/3 = smaller value, 9 = larger value

    5) 29/b - 23 = -22/(b+1)

    (29-23b)/b = -22/(b+1)

    (29-23b)(b+1) = -22b

    6b-23b²-29 = -22b

    -23b²+28b-29 = 0

    23b²-28b+29 = 0

    x = (28±i√1884)/46 = (28-i√1884)/46 = smaller value, (28+i√1884)/46 = larger value

  • Anonymous
    9 years ago

    Q1

    2x^2 -3x -35=0

    (2x+7)(x-5)=0 ........... (check you get factorisation correct by multiplying it back out!)

    x=-7/2 or x=5

    Q2

    to use formula must be in form

    ax^2 + bx+ c

    5x^2 +45x +65 =0

    a=5, b=45 c=65

    gives -9 plusminus root29 all over 2

    Q3

    multiply everything by x to remove the "over x"

    x(x-2)=8

    x^2 -2x -8=0

    then solve as normal

    Q4

    as above but first multiply by (x-1) and then by (x-5). Simplify as needed, rearrange as solve as normal

    Q5

    similar but replaced the x's with b's

  • Anonymous
    9 years ago

    3/

    x(x-2)=8

    x^2 - 2x - 8 = 0

    (x-4)(x+2)=0 ---> x = 4 or -2

    4/

    LCD = (x-1)(x-5)

    8(x-5)+8(x-1) = 3(x-1)(x-5)

    expand , simplify then solve for x

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    Lv 4
    4 years ago

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