Question x-x-1-

2.2 Nonlinear Equations in One Variable - Quadratic solving (factoring, quadratic formula, completing square)
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x x + 1 - 56 = 4 x x - 7

What is the sum of the solutions to the given equation?

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x x + 1 - 56 = 4 x x - 7 What is the sum

Hard-difficulty · SAT Math · Nonlinear Equations in One Variable — Quadratic solving (factoring, quadratic formula, completing square). Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

The correct answer is 293. Applying the distributive property to the left-hand side of the given equation, xx+1-56, yields x2+x-56. Applying the distributive property to the right-hand side of the given equation, 4xx-7, yields 4x2-28x. Thus, the equation becomes x2+x-56=4x2-28x. Combining like terms on the left- and right-hand sides of this equation yields 0=4x2-x2+-28x-x+56, or 3x2-29x+56=0. For a quadratic equation in the form ax2+bx+c=0, where a , b , and c are constants, the quadratic formula gives the solutions to the equation in the form x=-b/mo>b2-4ac2a. Substituting 3 for a , -29 for b , and 56 for c from the equation 3x2-29x+56=0 into the quadratic formula yields x=29/mo>-292-435623, or x=296/mo>136. It follows that the solutions to the given equation are 296+136 and 296-136. Adding these two solutions gives the sum of the solutions: 296+136+296-136, which is equivalent to 296+296, or 293. Note that 29/3, 9.666, and 9.667 are examples of ways to enter a correct answer.