## anonymous 4 years ago I need to finish my homework ASAP! someone please help!! :( A square has sides of length 3x cm. A rectangle is 2x cm by (x+7)cm. The area of the square is twice that of the rectangle. Find the dimensions of each figure.

1. anonymous

area of the square is 9 , areas of the rectangle is $2x(x+3)$ and twice that number is 9 so solve $4x(x+3)=9$ $4x^2+12x-9=0$via the quadratic formula

2. anonymous

thats it?

3. anonymous

the area of the rectangle is (2x)(x+7) = A and the area of the square is twice that of the rectangle. Therefore area of the square = 2A . so we know (2x)(x+7) = A and (3x)^2 = 2A . so (3x)^2 = 2[ (2x)(x+7)] ====> 9x^2 = 4x^2 + 28x ====> 5x^2 = 28x ====> x = 28/5 . Now verify if my solution is correct by plugging in the value of x and finding the area of the rectangle and square

4. anonymous

oh i was wrong, sorry. it says side is 3x, not 3. so malcolm is right and i am wrong

5. anonymous

$4x(x+7)=9x^2$ $4x^2+28x=9x^2$ $5x^2-28x=0$ $x(5x-28)=0$ $x=\frac{28}{5}$

6. anonymous

Satelite is this how I shall write the whole thingie?