which equation shows the quadratic formula used correctly to solve 7×2 = 9 + x for x?
Equation \( 7x^2 = 9+x \)
=> \( 7x^2 -x -9 =0 \) [Convert in Quadaratic Equation]
=> \( 7x^2 + (-1)x + (-9) =0 \)
The Quadratic Equation formula is
\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}.\)
where a = 7, b = -1 and c = -9
put the Value of a, b, and c in the quadratic equation formula
=> \(x = {-(-1) \pm \sqrt{(-)^2-4(7)(-9)} \over 2(7)}\)
=> \(x = {1 \pm \sqrt{1-4(-63)} \over 14}\)
=> \(x = {1 \pm \sqrt{1+ 252} \over 14}\)
=> \(x = {1 \pm \sqrt{253} \over 14}\)
=> \(x = {1 \pm 15.9 \over 14}\)
=> \(x = {16.9 \over 14} \;and\; { -14.9 \over 14}\) [convert in Decimal Form]
=> \(x = {1.2} \;and\; {-1.06}\)