Question

Which equation shows the quadratic formula used correctly to solve 7x^2=9+x for x?

Answer 1

7x^2 = 9 + x
7x^2 - x - 9 = 0

(1 +/-√ -1^2 - 4(7)(-9)) / 2(7)

(1 +/-√ 1 + 252) / 14

(1 +/-√  252) / 14


x =1/14 + 1/14 √253 
x=1/14 + −1/14 √253

Answer 2

Answer:

$x=\dfrac{1-\sqrt{253}}{14},\dfrac{1+\sqrt{253}}{14}$

Step-by-step explanation:

Given: $7x^2=9+x$

Standard form of quadratic equation:

$ax^2+bx+c=0$

$7x^2-x-9=0$

Quadratic formula:

$x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$

where,

• a is coefficient of x², a=7
• b is coefficient of x, b=-1
• c is constant term, c=-9

Substitute the value into formula

$x=\dfrac{1\pm\sqrt{1^2-4(7)(-9)}}{2(7)}$

$x=\dfrac{1\pm\sqrt{253}}{14}$

$x=\dfrac{1-\sqrt{253}}{14},\dfrac{1+\sqrt{253}}{14}$

Hence, All the above steps to solve for x using quadratic formula.