What factorization can be used to reveal the zeros of f(x) = -12x² - 11x + 15 ?
A.) f(x) = -x(12x + 11) + 15 B.) f(x) = (-4x + 3)(3x + 5) C.) f(x) = -(4x + 3)(3x + 5) D.) f(x) = (4x + 3)(-3x + 5)
f(x) = -12x² - 11x + 15
= -1(12x² + 11x - 15) {factored -1 out} = -(12x² + 20x - 9x - 15) {factoring by grouping......split the middle term, 11x, into 20x and -9x} = -[4x(3x + 5) - 3(3x + 5)] {factored 4x out of first two terms and -3 out of last two terms} = -(3x + 5)(4x - 3) {factored out the common factor, (3x + 5)} Looking at the answer choices, the only one that matches is: B.) f(x) = (-4x + 3)(3x + 5) {distributed negative sign to (4x - 3)} Ask Algebra House Comments are closed.
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