Question

In the following equation, identify the x-intercepts in the graph y = 3x2 + 19x – 40.

How do I begin to solve this?

Answer 1

I remember you :D
So... x-intercept... where the graph touches the x-axis. That's fancy talk. To get the x-intercepts, simply set y = 0, and solve.

I know you can do this... you've done it quite a few times last time ;)

Answer 2

The x-intercepts are where the graph crosses the x-axes: or in other words when \(y=0\).
So to begin we allow:
\(y=3x^2 + 19x – 40=0 \)
upon solving this quadratic equation, we have the x-intercepts of the graph!

Answer 3

What he/she said ^ :)
If you're stuck, keep this in mind, and you'll never go wrong with quadratics :)
Whenever you're faced with solving a quadratic equation in the form
ax² + bx + c = 0
Then remember this formula, and you'll be able to regularly get the solutions for x...
\[\huge x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\]

Answer 4

(3x - 5)(x + 8) = 0

Answer 5

Or you could do that :D
So, remember how to proceed from here? At least one of these factors must be zero, so check both cases.

Answer 6

@beesknees01 Excellent!

Answer 7

x = 5/3 x=- 8

Answer 8

Brilliant ;)

Answer 9

thank you!

Answer 10

Y intercepts occurs when X=0 and hence X intercepts occur when y=o
Therfore
if y=0, it follows that....
0=3X^2=19X-40
using the quadratic formular.....