Solve for specified variable?

The question asks to solve for b

1/a + 1/b = c

I got

b=a/ca-1

Is this right?

And second question is:

If f(x) = x^2 - 8x, find f(a+h)

Last but not least:

Factor Completely

x^2 - 14x + 49 - y^2

Please Help!!

2 Answers

Relevance
  • PaulR2
    Lv 7
    8 years ago
    Favorite Answer

    1)

    ( 1 / a ) + ( 1 / b ) = c

    Common denominator

    ( b / ab ) + ( a / ab ) = c

    Combine like terms

    ( b + a ) / ( ab ) = c

    Multiply by ab

    ( b + a ) = cab

    Divide by b

    1 + ( a / b ) = ca

    Subtract 1

    ( a / b ) = ca - 1

    Multiply by b

    a = b(ca - 1)

    Divide by (ca - 1)

    b = ( a ) / ( ca - 1 )

    2) All you do here is plug in ( a + h ) for x

    f(x) = x² - 8x

    f(a + h) = (a + h)² - 8(a + h)

    f(a + h) = a² + 2ah + h² - 8a - 8h

    f(a + h) = a² + h² + 2ah - 8a - 8h

    3) This one you just have to notice the perfect square trinomial

    x² - 14x + 49 - y²

    (x - 7)² - y²

    I hope this helps. Have a good day.

  • 8 years ago

    1.

    b = a/(ac - 1)

    2.

    f(x) = x² - 8x

    f(a + h) = (a + h)² - 8(a + h) = a² + 2ah + h² - 8a - 8h

    3.

    x² - 14x + 49 - y² =

    = (x² - 14x + 49) - y² =

    = (x - 7)² - y² = .............A² - B² = (A + B)(A - B)

    = (x - 7 + y)(x - 7 - y)

Still have questions? Get your answers by asking now.