5.In the following equation, identify the x-intercepts in the graph y = 3x^2 + 19x – 40.

I'm stuck on this problem can anyone help? :)

Question

5.In the following equation, identify the x-intercepts in the graph y = 3x^2 + 19x – 40. 

I'm stuck on this problem can anyone help? :)

mathslover · Answer

You mean to say that we have to find x intercept?

anonymous · Answer

Where are you having problem??

mathslover · Answer

Ok so just put y =0 :
$$\large{0=3x^2+19x-40}$$
$$\large{0=3x^2+24x-5x-40}$$
$$\large{0=3x(x+8)-5(x+8)}$$
$$\large{0=(3x-5)(x+8)}$$

anonymous · Answer

For finding x intercept we put y = 0..

anonymous · Answer

Oh okay, sry I forgot about that and yeah had trouble factoring it and now I see. This means our x= -8 and 5/3

anonymous · Answer

Yep..

mathslover · Answer

right

mathslover · Answer

3x-5=0                              x+8=0
3x=5                                     x=-8 
x=5/3

anonymous · Answer

Right, I'd also like to add that in case you forget whether to make the y or the x zero when it comes to either intercept remember that any x-intercept would have to be (x, 0) and that any y-intercept would have to be (0, y). Cheers

anonymous · Answer

K thx a ton :)