You may want to review solving equations by factoring and mutiplying polynomials first.
If you know what solutions you want, you can write a quadratic equation with those solutions. Just take two linear functions whose x-intercepts are those two numbers. For example, if you want 4 to be a solution, take x − 4. If you want −3 ⁄ 4, you could take x + 3 ⁄ 4, but it would be better to use 4x + 3. Then multiply these two linear functions. For example, if we want the two solutions to be 4 and −3 ⁄ 4, we work out (x − 4)(4x + 3) = 4x2 − 13x − 12. Finally, we set that equal to 0 to get our equation, which is 4x2 − 13x − 12 = 0.
Remember, an equation must always have two sides separated by an equals sign. In these problems, though, I'll write the “= 0” for you.