Question

Solve for x 2x^2 + 7x -15 = 0

Answer 1

Answer:

x = 3/2, x = -5

Step-by-step explanation:

    2x² + 7x - 15 = 0

You're going to factor first using whichever method you prefer, but it's best to always start with GCF over any other method. In this case, this equation does not have one so we'll go with the Lie method and grouping method.

A quadratic is formulated to look like this:

    ax² + bx + c = 0

So to start factoring, we're going to multiply "a" and "c" to get -30.

Then, we are going to look at factors of -30 that will add up to "b" and in this case, 10 and -3 multiply to get -30 but also add up 7 so we plug those two numbers in.

    2x² + 10x - 3x - 15 = 0

Now, we are going to group them like so:

    (2x² + 10x)(-3x - 15) = 0

Finally, we can begin to break it down and find x.

    2x(x+5) - 3(x+5) = 0

You're doing this right, if the information in the parentheses match.

    (x+5)(2x-3) = 0

Set both (x+5) and (2x-3) to zero and solve.

x = 3/2 and x = -5