Find the y-intercept for the parabola defined by this equation y=5x2-x-6

insens350 [35]

Answer:

Question 4: $y=\displaystyle -\frac{4}{5}x$

Question 5: $y=-5x-3$

Step-by-step explanation:

Hi there!

Linear equations are typically organized in slope-intercept form: $y=mx+b$ where m is the slope of the line and b is the y-intercept (the y-coordinate of the point where the line crosses the y-axis).

Question 4

1) Determine the slope (m)

$\displaystyle m=\frac{y_2-y_1}{x_2-x_1}$ where two points that pass through the line are $(x_1,y_1)$ and $(x_2,y_2)$

In the graph, two easy-to-identify points on the line are (-5,4) and (5,-4). Plug these into the equation:

$\displaystyle m=\frac{-4-4}{5-(-5)}\\\\\displaystyle m=\frac{-4-4}{5+5}\\\\\displaystyle m=\frac{-8}{10}\\\\\displaystyle m=-\frac{4}{5}$

Therefore, the slope of the line is $\displaystyle -\frac{4}{5}$ . Plug this into $y=mx+b$ as the slope (m):

$y=\displaystyle -\frac{4}{5}x+b$

2) Determine the y-intercept (b)

On the graph, we can see that the line crosses the y-axis when y is 0. Therefore, the y-intercept (b) is 0. Plug this into $y=\displaystyle -\frac{4}{5}x+b$ :

$y=\displaystyle -\frac{4}{5}x+0\\\\y=\displaystyle -\frac{4}{5}x$

Question 5

1) Determine the slope (m)

$\displaystyle m=\frac{y_2-y_1}{x_2-x_1}$

Two easy-to-identify points are (-1,2) and (0,-3). Plug these into the equation:

$\displaystyle m=\frac{-3-2}{0-(-1)}\\\\\displaystyle m=\frac{-3-2}{0+1}\\\\\displaystyle m=\frac{-5}{1}\\\\m=-5$

Therefore, the slope is -5. Plug this into $y=mx+b$ :

$y=-5x+b$

2) Determine the y-intercept (b)

On the graph, we can see that the line crosses the y-axis at the point (0,-3). The y-coordinate of this point is -3. Therefore, the y-intercept (b) is -3. Plug this into $y=-5x+b$ :

$y=-5x+(-3)\\y=-5x-3$