Astudent solved this problem and said the answer was 78.

there were 171 people who came to the play in the afternoon. in the evening, there were 93 more people at the play than in the afternoon. how many people came to the play in the evening?

which estimation strategy correctly checks whether the student’s answer is reasonable?

a.
the student’s answer is reasonable. estimation: 170 – 90 = 80

b.
the student’s answer is not reasonable. estimation: 170 + 90 = 260

c.
the student’s answer is not reasonable. estimation: 175 + 100 = 275

d.
the student’s answer is not reasonable. estimation: 200 – 100 = 100

step-by-step explanation:

equation

you are asked to write the equation

  expression = 0

using the given expression. when you do that, you have

  2x^2-2x-12 = 0

factoring

you can see that each of the coefficients is even, so a factor of 2 can be removed immediately.

  2(x^2 -x -6) = 0

if you multiply the binomials (x+a)(x+b), you get

  (x +a)(x +b) = x^2 +(a+b)x +ab

this tells you the coefficient of x is the sum of two factors of the constant term. here, that means -1 is the sum of two factors of -6. we want to know those factors so we can factor the trinomial.

  -6 = -1×6 = -2×3 = -3×2 = -6×1

the factor pair that sums to -1 is {-3, 2}, so our factorization is

  2(x -3)(x +2) = 0

solutions

the solutions to this equation are the values of x that make the product zero. a product is zero only when only of the factors of the product is zero. here, that means

  x - 3 = 0

  x = 3 . . . add 3 to both sides of the equation

or

  x +2 = 0

  x = -2 . . . add -2 to both sides of the equation

the solutions to the equation are x=3 or x=-2. both of these values of x satisfy the equation—they make it be true.

x

step-by-step explanation: