Multiply 3x 53x 5 9x230x25 9x2 30x 25 9x225 9x2 25 The

Multiply. (3x + 5)(3x - 5) 9x^2-30x-25 9x^2 + 30x + 25 9x^2-25 9x^2 + 25 The area of a rectangular painting is given by the trinomial x^2 + 4x - 21. What are die possible 0 point) dimensions of the painting? Use factoring.

Solution

5. (3x +5)(3x -5) = (3x)² -(5)² = 9x² - 25. The 3rd answer is correct [ as (a +b)(a - b) = a² - b² ]

6. x²+ 4x -21 = x² + 7x -3x - 21 = x( x+7) -3(x + 7) = ( x + 7)(x -3). Thus, the dimensions of the painting are (x + 7) and ( x - 3). The last answer is correct.