Question

Given that the quadratic equation 3x^2+bx-2 has x-intercept {-2, 4}. What is the "b" value.

Answer 1

The value of b is $b=3$

Explanation:

The given quadratic equation is $y=3x^{2} +bx-2$

And has x - intercept $(-2,4)$

To determine the value of b, let us substitute the coordinates $(-2,4)$ in the given quadratic equation $y=3x^{2} +bx-2$

Substituting the x - intercept in the equation $y=3x^{2} +bx-2$, we have,

$4=3(-2)^{2} +b(-2)-2$

Simplifying, we have,

$4=3(4)-2b-2$

$4=12-2b-2$

Adding the constant terms, we get,

$4=10-2b$

Subtracting both sides by 10, we have,

$-6=-2b$

Dividing both sides by -2, we get,

$b=3$

Hence, the value of b is $b=3$