Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

I need help solving this word problem relating to quadratic equations?

I don't understand what the words in the inverted comas mean, and please keep it as simple as possible i am pretty dumb

The perimeter of a square exceeds that of another by 100cm and "the area of the larger square exceeds three times the area of the smaller square by 325cm sq" .Find length of a side of each of the squares.

2 Answers

Relevance
  • ?
    Lv 7
    7 years ago
    Favorite Answer

    inverted com(m)as = quotation marks

    let a = side of a square and b = side of another square, a and b both greater than 0

    "The perimeter of a square exceeds that of another by 100cm"

    The perimeter of a square is 4 times the length of a side

    4a = 4b+100

    "the area of the larger square exceeds three times the area of the smaller square by 325cm sq

    The area of a square is the square of the length of a side

    a² = 3b² + 325

    You have two independent equations in two unknowns so you can solve them for the values of the unknowns.

    4a = 4b+100 → a = b+25

    a² = 3b² + 325 → (b+25)² = 3b² + 325

    b² + 50b + 625 = 3b² + 325

    2b² - 50b - 300 = 0

    b² - 25b - 150 = 0

    (b-30)(b+5) = 0

    b = -5, 30 ← discard the negative value since b > 0

    b = 30

    Now that we know b, we can use the equation a = b+25 to find a

    a = 30+25 = 55

    We now know that the length of the side of the smaller square is 30cm and the length of the larger square is 55cm.

    =====================================

    Check:

    Perimeter:

    Pa = 4(55) = 220cm

    Pb = 4(30) = 120cm

    difference = 100cm ← Checks

    Area:

    Aa = 55² = 3025cm²

    Ab = 30² = 900cm²

    3025 - 3*900 = 325cm² ← Checks

  • 7 years ago

    Let, a and b be the sides of the two squares.

    4b = 4a + 100

    this implies that b = a + 25

    b^2 = 3a^2 + 325

    Substituting value of b in this 2nd equation, we get,

    (a + 25)^2 = 3a^2 + 325

    a^2 + 625 + 50a = 3a^2 + 325

    2a^2 - 50a - 300 = 0

    a^2 -25a - 150 = 0

    a = {25 +- sqrt[25^2 - 4(1)(-150)]}/2

    a = {25 +- 35}/2

    a = 30, -5

    but a can't be -ve, so a = 30

    therefore, b = a + 25 = 30 + 25 = 55

Still have questions? Get your answers by asking now.