Solve 2x^2 - 5x = 21

Evaluate

2 x^{2} - 5 x = 21

Move the expression to the left side

2 x^{2} - 5 x - 21 = 0

Substitute a= 2,b= - 5 and c= - 21 into the quadratic formula x = \frac{- b \pm b ^{2} - 4 a c}{2 a}

x = \frac{5 \pm ( - 5 ) ^{2} - 4 \times 2 ( - 21 )}{2 \times 2}

Simplify the expression

x = \frac{5 \pm ( - 5 ) ^{2} - 4 \times 2 ( - 21 )}{4}

Simplify the expression

More Steps

x = \frac{5 \pm 193}{4}

Separate the equation into 2 possible cases

x = \frac{5 + 193}{4} x = \frac{5 - 193}{4}

Solution

x_{1} = \frac{5 - 193}{4}, x_{2} = \frac{5 + 193}{4}

Alternative Form

x_{1} \approx - 2.223111, x_{2} \approx 4.723111

Solve the quadratic equation