Dorothy was solving the following quadratic equation by factoring: 2x^2 + 7x -15 = 0. Which choice shows the correctly factored form of this equation?

A: (2x - 3) (x + 5) = 0

B: (2x -3) ( x -5) = 0

C: (5x - 3) (x + 2) = 0

D: (5x - 3) ( x- 2) = 0

1 answer

To factor the quadratic equation \( 2x^2 + 7x - 15 = 0 \), we will look for two numbers that multiply to \( 2 \cdot (-15) = -30 \) and add up to \( 7 \).

The numbers that satisfy these conditions are \( 10 \) and \( -3 \) since \( 10 \cdot (-3) = -30 \) and \( 10 + (-3) = 7 \).

Now, we can rewrite the quadratic equation:

\[ 2x^2 + 10x - 3x - 15 = 0 \]

Next, we will group the terms:

\[ (2x^2 + 10x) + (-3x - 15) = 0 \]

Now, factor by grouping:

\[ 2x(x + 5) - 3(x + 5) = 0 \]

This can be factored as:

\[ (2x - 3)(x + 5) = 0 \]

Thus, the correct factored form of the equation \( 2x^2 + 7x - 15 = 0 \) is:

\[ (2x - 3)(x + 5) = 0 \]

Therefore, the answer is:

A: \( (2x - 3)(x + 5) = 0 \).