Solved on Dec 20, 2023

Solve the quadratic equation 2x214x=202x^2 - 14x = -20 by graphing the corresponding function.

STEP 1

Assumptions
1. We are given a quadratic equation 2x214x=202x^2 - 14x = -20.
2. We need to solve this equation by graphing the corresponding function.
3. To graph the function, we will first convert the equation into standard form y=ax2+bx+cy = ax^2 + bx + c.

STEP 2

First, we need to move all terms to one side of the equation to get it into the standard form.
2x214x+20=02x^2 - 14x + 20 = 0

STEP 3

Now, we identify the coefficients for the quadratic equation in standard form, where a=2a = 2, b=14b = -14, and c=20c = 20.

STEP 4

The corresponding function to graph is y=2x214x+20y = 2x^2 - 14x + 20.

STEP 5

To graph the function, we will find the vertex of the parabola. The x-coordinate of the vertex is given by b2a-\frac{b}{2a}.
xvertex=1422x_{vertex} = -\frac{-14}{2 \cdot 2}

STEP 6

Calculate the x-coordinate of the vertex.
xvertex=144=144=3.5x_{vertex} = -\frac{-14}{4} = \frac{14}{4} = 3.5

STEP 7

Now, we will find the y-coordinate of the vertex by plugging xvertexx_{vertex} into the function y=2x214x+20y = 2x^2 - 14x + 20.
yvertex=2(3.5)214(3.5)+20y_{vertex} = 2(3.5)^2 - 14(3.5) + 20

STEP 8

Calculate the y-coordinate of the vertex.
yvertex=2(12.25)49+20y_{vertex} = 2(12.25) - 49 + 20

STEP 9

Simplify the calculation for the y-coordinate.
yvertex=24.549+20y_{vertex} = 24.5 - 49 + 20

STEP 10

Finish calculating the y-coordinate of the vertex.
yvertex=4.5y_{vertex} = -4.5

STEP 11

The vertex of the parabola is at the point (3.5,4.5)(3.5, -4.5).

STEP 12

Next, we will find the y-intercept of the parabola by setting x=0x = 0 in the function y=2x214x+20y = 2x^2 - 14x + 20.
yintercept=2(0)214(0)+20y_{intercept} = 2(0)^2 - 14(0) + 20

STEP 13

Calculate the y-intercept.
yintercept=00+20=20y_{intercept} = 0 - 0 + 20 = 20

STEP 14

The y-intercept of the parabola is at the point (0,20)(0, 20).

STEP 15

To find the x-intercepts (the solutions to the equation), we set y=0y = 0 and solve for xx.
0=2x214x+200 = 2x^2 - 14x + 20

STEP 16

We can solve for the x-intercepts by factoring the quadratic equation, if possible, or using the quadratic formula. Let's try factoring first.

STEP 17

We look for two numbers that multiply to 220=402 \cdot 20 = 40 and add up to 14-14. These numbers are 10-10 and 4-4.

STEP 18

Factor the quadratic equation using these numbers.
0=(2x10)(x4)0 = (2x - 10)(x - 4)

STEP 19

Set each factor equal to zero and solve for xx.
2x10=0orx4=02x - 10 = 0 \quad \text{or} \quad x - 4 = 0

STEP 20

Solve the first equation for xx.
2x=102x = 10
x=5x = 5

STEP 21

Solve the second equation for xx.
x=4x = 4

STEP 22

The x-intercepts of the parabola are at the points (5,0)(5, 0) and (4,0)(4, 0).

STEP 23

Now we have enough points to sketch the graph of the parabola: the vertex (3.5,4.5)(3.5, -4.5), the y-intercept (0,20)(0, 20), and the x-intercepts (5,0)(5, 0) and (4,0)(4, 0).

STEP 24

Plot these points on a coordinate plane and draw a smooth curve through them to represent the parabola.

STEP 25

The points where the parabola crosses the x-axis represent the solutions to the original equation.

STEP 26

The solutions to the equation 2x214x=202x^2 - 14x = -20 by graphing are x=5x = 5 and x=4x = 4.
The solutions to the equation by graphing are x=5x = 5 and x=4x = 4.

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