Practice Quadratic Formula in Math

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A formula giving the exact solutions to any quadratic equation ax2+bx+c=0ax^2 + bx + c = 0 directly from its three coefficients.

When factoring fails, this formula always finds the x-intercepts.

Showing a random 20 of 50 problems.

Example 1

medium
Solve 5x2โˆ’2xโˆ’3=05x^2 - 2x - 3 = 0.

Example 2

easy
Solve x2โˆ’4x+4=0x^2 - 4x + 4 = 0.

Example 3

medium
Solve x2โˆ’4x+1=0x^2 - 4x + 1 = 0. Leave answers in exact form.

Example 4

medium
Solve x2โˆ’6x+13=0x^2 - 6x + 13 = 0.

Example 5

challenge
If the roots of x2โˆ’8x+k=0x^2 - 8x + k = 0 are in the ratio 3:13 : 1, find kk.

Example 6

medium
Solve x+6x=5x + \frac{6}{x} = 5.

Example 7

challenge
Find all values of aa for which x2+ax+4=0x^2 + ax + 4 = 0 has two distinct positive real roots.

Example 8

easy
Solve x2+2xโˆ’8=0x^2 + 2x - 8 = 0.

Example 9

medium
A rectangular garden has area 5454 mยฒ and its length is 33 m more than its width. Find the width.

Example 10

easy
Find the discriminant of 5x2โˆ’3x+1=05x^2 - 3x + 1 = 0 and state how many real roots the equation has.

Example 11

medium
Solve 2x2+xโˆ’6=02x^2 + x - 6 = 0.

Example 12

challenge
Prove that for any real aa, the equation x2+ax+(aโˆ’1)=0x^2 + ax + (a - 1) = 0 has at least one real solution.

Example 13

easy
Solve 2x2โˆ’4xโˆ’6=02x^2 - 4x - 6 = 0.

Example 14

medium
Solve 3x2โˆ’4xโˆ’4=03x^2 - 4x - 4 = 0 using the quadratic formula.

Example 15

hard
A projectile follows h(t)=โˆ’5t2+25t+1h(t) = -5t^2 + 25t + 1 metres. When does it reach height 2020 m? Give all solutions to two decimal places.

Example 16

hard
Find values of kk such that x2+(k+2)x+9=0x^2 + (k+2)x + 9 = 0 has no real roots.

Example 17

easy
Solve x2โˆ’5x+6=0x^2 - 5x + 6 = 0 using the quadratic formula.

Example 18

medium
Solve x2+5xโˆ’14=0x^2 + 5x - 14 = 0.

Example 19

hard
Solve x4โˆ’10x2+9=0x^4 - 10x^2 + 9 = 0.

Example 20

medium
Find the values of kk for which x2+kx+4=0x^2 + kx + 4 = 0 has a double root.