## AriPotta 2 years ago can someone tell me how to do this? i forgot :x

1. yrelhan4

what does x intercept mean? y is 0? or x is 0? refer to the cartesian plane.

2. yrelhan4

|dw:1362416956027:dw| this is called the cartesian plane. x intercept means what length does the curve cut from the origin.

3. yrelhan4

origin is the intersection of x and y axis

4. yrelhan4

as i said, x intercept is the length the curve cuts on the x axis. so we have to find where the curve cuts the axis. what would put equal to 0? y no? correction: not from the origin in case of any curve. only in case of a staright line.

5. yrelhan4

yup. you would get two points. the distance between those points will give you the length of intercept.

6. yrelhan4

3x^2 + 19x – 40=0 solve.. take your time.

7. yrelhan4

i deleted that. do it yourself. you'll learn better.

8. yrelhan4

suppose the general equation is ax^2 +b x + c when you have to solve this equation you always have to find those two numbers whose product is a*c and sum is b. likewise, if you have ax^2 +b x - c , sum of the numbers has to be b and product has to be a*-c. here, you have to find two number whose product is -120 and sum is 19.

9. yrelhan4

can you now find those 2 numbes?

10. yrelhan4

no no. those number arent the roots. you have to do this way. 3x^2+19x-40=0 -->3x^2 +24x -5x -40=0 -->3x(x+8) - 5(x+8)=0 taking x+8 common (3x-5)(x+8)=0 x=5/3,-8 we still dont have the intercept. first tell me if you got this.

11. yrelhan4

basically we have to resolve 19 into 2 numbers which have the product -120 and sum 19. it makes our job to find x easier.

12. yrelhan4

yes. it can be confusing. take your time. i'll recommend watching some vids on how to find roots. they can be really helpful.

13. yrelhan4

nope. x intercept is the length the curve cuts on the x axis. so basically the points you have are where the curve cuts the x axis right? |dw:1362419151119:dw| so what you would have to is. calculate the distance between 5/3 and 0(origin) and 0(origin) and -8. these would be 5/3 and 8 respectively. add them and you have your answer.

14. yrelhan4

oh dang. yeah it means the points. i was confusing it with something else. :o

15. yrelhan4

you're welcome. :)