Question

[9.02] Where does the graph of y = 3x2 + 14x − 5 cross the x-axis?
Medals to the best answer!

Answer 1

3x^2
Sorry, that was a mistake

Answer 2

crosses the x-axis when y = 0

3x^2 + 14x - 5 = 0

you should use the quadratic formula on the polynomial: ax^2 + bx + c above, which states that:

\[x_{1,2} = \frac{ -b \pm \sqrt{b^{2} - 4ac} }{ ? }\]

x1,2 is for the 2 x values that you will get (one for plus, one for minus). they can be the same

Answer 3

rewriting the quadratic formula:

\[x_{1,2} = \frac{ -b \pm \sqrt{b^{2} - 4ac}} { 2a }\]

Answer 4

our case:

\[x1,2 = \frac{ -14 \pm \sqrt{14^{2} - (4\times3\times (-5))} }{ 2(3) }\]

Answer 5

How do I finish? @Euler271

Answer 6

you have 2 answer:

\[x1 = \frac{ -14 - \sqrt{256} }{ 6 }\]
\[x2 = \frac{ -14 + \sqrt{256} }{ 6 }\]

Answer 7

once you simplify with calculator, you are done

Answer 8

Thank you!:)