Solved on Jan 19, 2024

Find the number(s) xx such that 2x212=5x2x^2 - 12 = -5x.

STEP 1

Assumptions
1. Let the unknown number be represented by x x .
2. The phrase "twelve less than twice the square of a number" can be written as 2x212 2x^2 - 12 .
3. The phrase "equal to the product of -5 and the number" can be written as 5x -5x .
4. We are looking for the value(s) of x x that satisfy the equation 2x212=5x 2x^2 - 12 = -5x .

STEP 2

Write the given equation using the assumptions.
2x212=5x 2x^2 - 12 = -5x

STEP 3

To solve for x x , we need to set the equation to zero. Move all terms to one side of the equation to form a quadratic equation.
2x2+5x12=0 2x^2 + 5x - 12 = 0

STEP 4

Now we need to solve the quadratic equation. First, we can try to factor the quadratic if possible.

STEP 5

Look for two numbers that multiply to 2×12=24 2 \times -12 = -24 and add to 5 5 .

STEP 6

The numbers that satisfy these conditions are 8 8 and 3 -3 because 8×3=24 8 \times -3 = -24 and 8+(3)=5 8 + (-3) = 5 .

STEP 7

Write the quadratic equation in its factored form using these two numbers.
(2x3)(x+4)=0 (2x - 3)(x + 4) = 0

STEP 8

Now, we have the product of two factors equal to zero. According to the zero-product property, if the product of two factors is zero, then at least one of the factors must be zero.

STEP 9

Set each factor equal to zero and solve for x x .
2x3=0orx+4=0 2x - 3 = 0 \quad \text{or} \quad x + 4 = 0

STEP 10

Solve the first equation 2x3=0 2x - 3 = 0 for x x .
2x=3 2x = 3
x=32 x = \frac{3}{2}

STEP 11

Solve the second equation x+4=0 x + 4 = 0 for x x .
x=4 x = -4

STEP 12

We have found two solutions for x x that satisfy the original equation.
The solutions are x=32 x = \frac{3}{2} and x=4 x = -4 .

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