Factor a quadratic expression to reveal the zeros

The expression 3x² - 33x - 180 can be factored into the form a(x + b)(x + c), where a, b, and c are constants, to reveal the zeros of the function defined by the expression. What are the zeros of the function defined by 3x² - 33x - 180?
A.)  -15     B.)  -10     C.)  -6     D.)  -4     E.)  4     F.)  6     G.)  10     H.)  15

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Zeros of a quadratic trinomial are the values for x, when y is set equal to zero.  Zeros of a quadratic function are also known as "x-intercepts", "roots", or "solutions".  When a graph hits the x-axis,
at the x-intercept, the value of y is zero.

3x² - 33x - 180 = 0   {set the expression equal to 0, to find the zeros of the function}
3(x² - 11x - 60)   {factored out the greatest common factor, 3}
3(x - 15)(x + 4) = 0   {factored the quadratic trinomial into two binomials}
x - 15 = 0   or   x + 4 = 0   {set each factor equal to 0, of course excluding the 3}
x = 15   or   x = -4   {solved each equation for x}

the zeros are  D.) -4   and   H.) 15

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