Question

Determine an equation of a quadratic function with x intercepts of -3 and 5 that passes through the point A(4,-21)

Answer 1

Answer: y = 21x + -105 or y = 21x - 105

Step-by-step explanation:

Our equation is going to be in the format of y = mx+b, where m is the slope, and b is the y-intercept.

For this, you can find the slope by doing

(y₁-y₂)÷(x₁-x₂)

So we just sub in one of the x intercept points and the point that we already have, so let's do (-21-0)/(4-5). That is equal to 21, therefore, 21 is our slope.

So we have y = 21x + b, so now we can sub in one of our points for y and x in the equation. Let's do (4,-21).

-21 = 21(4) + b

-21 = 84 + b

-105 = b

So our equation is y = 21x + -105, meaning we have a slope of 21 and a y intercept of -105.

Edit: you can also do y = 21x - 105