SOLUTION: The length of a rectangle is 1 cm longer than its width. If the diagonal of the rectangle is 4 cm, what are the dimensions (the length and the width of the rectangle? x^2 + (x +

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: The length of a rectangle is 1 cm longer than its width. If the diagonal of the rectangle is 4 cm, what are the dimensions (the length and the width of the rectangle? x^2 + (x +      Log On


   



Question 90301This question is from textbook Beginning Al
: The length of a rectangle is 1 cm longer than its width. If the diagonal of the rectangle is 4 cm, what are the dimensions (the length and the width of the rectangle?
x^2 + (x + 1)^2 = 4^2
x^2+ x^2 + 2x + 1 = 16
2x^2 + 2x + 1 -16 = 0
2x^2 + 2x -15 = 0
x^2 + x -15/2 = 0
I think the above is correct, but now I don't know what to do...
This question is from textbook Beginning Al

Answer by ptaylor(2198) About Me  (Show Source):
You can put this solution on YOUR website!
YOU WERE ALMOST THERE!!!!!!!!!!!!!!!
Let x=width
Then x+1=length
x^2+(x+1)^2=4^2 get rid of parens
x^2+x^2+2x+1=16
2x^2+2x+1-16=0
2x^2+2x-15=0 quadratic in standard form. We can solve using the quadratic formula
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x+=+%28-2+%2B-+sqrt%28+2%5E2-4%2A2%2A%28-15%29+%29%29%2F%282%2A2%29+
x+=+%28-2+%2B-+sqrt%28124%29%29%2F%284%29+
We'll not worry about the negative value for x, since lengths and widths are positive
x+=+%28-2+%2B+11.1355%29%2F%284%29+
x+=+%289.1355%29%2F%284%29+
x+=+2.284+cm----------------------width
x%2B1=2.284%2B1=3.284cm-----------------length
CK
2.284%5E2%2B3.284%5E2=4%5E2
5.216%2B10.785=16
16.001~~16

Hope this helps---ptaylor