SOLVING QUADRATIC EQUATIONS USING THE FORMULA

Quadratic equations of the form ax2 + bx + c = 0 can be solved using the formula:

1 Solve the equation x2 + 2x − 5 = 0. Give your answers correct to 2 decimal places. a = 1 b = 2 c = −5 and or or

2 Solve the equation 3x2 − 8x + 2 = 0. Give your answers correct to 2 decimal places. a = 3 b = −8 c = 2 and or or

3 Solve the equation x(x + 1) + (x – 1)(x + 2) = 3. Give your answers correct to 2 decimal places. expand the brackets write in the form ax2 + bx + c = 0 a = 2 b = 2 c = −5 and or or

4 The area of the rectangle is 30 cm2. Find the base of the rectangle. x + 3 expand the brackets and write in the form ax2 + bx + c = 0 x a = 1 b = 3 c = −30 and or The length of the base must be positive, so x = 4.18 or