Question

find the x-intercept of the function y=x^2 + x - 2

Answer 1

x intercept means y = 0
x^2 + x -2 = 0
can you solve it ?

Answer 2

no how do i solve it?

Answer 3

two options ..
you may use :
ax^2 + bx + c = 0
\[x = \frac{ -b \pm \sqrt{b^2 - 4ac} }{ 2a }\]

Answer 4

in this case a = 1 , b = 1 , c = -2

Answer 5

another way is factoring it directly

Answer 6

the square root is above b^2-4ac

Answer 7

dont know why it looks like its above b^2

Answer 8

can you do it using the formula i wrote ?

Answer 9

In this case I would definitely factor. Very quick and easy.

Answer 10

yes, i am trying to factor it though thats the way my teacher wants it done.

Answer 11

i would get (x+2)(x-1)?

Answer 12

Yep.

Answer 13

ok so in order to factor
ax^2 + bx + c
you have to split the middle term 'b' into b1 and b2
those b1 and b2 should satisfy :
b1 + b2 = b
b1 * b2 = a *c

in this case we can do :
x^2 + x -2 = 0
see here b =2 so we choose b1 =2 , b2 -1
b1 + b2 = 1
b1 *b2 = -2

then it becomes :
x^2 + 2x - x -2 = 0

can you factor it now ?

Answer 14

So the solutions are:
x+2 = 0
x-1 = 0

Answer 15

oh lol havent seen that you wrote it already!
yes (x+2)(x-1) = 0
now you know the solutions (x that satisfy the equation) ?

Answer 16

so there are two x-intercepts?

Answer 17

yes!

Answer 18

Indeed.

Answer 19

thanks!. so the intercepts would be (-2,0) and (1,0)?

Answer 20

yes.. very good

Answer 21

Myep.