Homework Help: Math

Posted by Shaw on Tuesday, June 30, 2009 at 2:47pm.

If the length of a rectangle is (2x-1)cm and its width is (x+3)cm.
How do i write an expression in the form ax^2+bx+c for the area of the rectangle?
Given that the area of the rectangle is 294cm^2, determine the value of x and state the dimensions of the rectangle in cms?? want the working so i can do questions like these in the future.

Math - Reiny, Tuesday, June 30, 2009 at 7:05pm
Area = length x width, so
Area = (2x-1)(x+3)

expand this and you got the first part

(did you get 2x^2 + 5x - 3 ?)

now set this equal to 294

2x^2 + 5x - 3 = 294
2x^2 + 5x - 297 = 0

rather than waste time trying to factor this with these numbers, I would use the quadratic formula

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