Question

Write an equation in which the quadratic expression 4x^2-26x+42 equals 0. Must show all work to receive credit.

Answer 1

Answer:

(a) (x + 3)(2x + 7) = 0

(b) These solutions mean that for these two x values, f(x) is equal to 0. It's also where the graph of f(x) crosses the x-axis.

Step-by-step explanation:

(a) We set 4x² -26x + 42 equal to 0:

4x² -26x + 42 = 0

Let's divide both sides by 2 to simplify this a bit:

2x² - 13x + 21 = 0

Now, we need factors a and b of 2 and c and d of 21 such that ac + bd = -13. The factors of 2 are: 1 and 2, so let's say a = 1 and b = 2. The factors of 21 are: (1, 21), (3, 7), (-1, -21), and (-3, -7). We see that if c = -7 and d = -3, this works:

ac + bd = 1 * (-7) + 2 * (-3) = -7 - 6 = -13

So, the factored form is:

(x - (-3))(2x - (-7)) = 0

(x + 3)(2x + 7) = 0

(b) So now we need to solve this. Set each of the two parenthetical expressions equal to 0:

x + 3 = 0

x = -3

AND

2x + 7 = 0

x = -7/2

These solutions mean that for these two x values, f(x) is equal to 0. It's also where the graph of f(x) crosses the x-axis.

Answer 2

Answer:

a) 2(x - 3)(2x - 7) = 0

b) function is 0 when x = 3 or 7/2

Step-by-step explanation:

4x² - 26x + 42 = 0

2(2x² - 13x + 21) = 0

2[2x² - 6x - 7x + 21] = 0

2[2x(x - 3) - 7(x - 3)] = 0

2(x - 3)(2x - 7) = 0

Solutions:.

x = 3, 7/2