Solve Quadratic Equation d^2 = 4(3d + 7)

Published on March 10, 2026

Algebra

This problem requires solving a quadratic equation by first expanding the expression and then factoring the resulting standard form equation to find the values of d.

Question

Answer

The problem asks to solve the quadratic equation:
Here is the step-by-step solution:
Step 1: Expand the right-hand side of the equation.
Step 2: Rearrange the equation into the standard quadratic form, .
Subtract and from both sides:
Step 3: Solve the quadratic equation.
We can solve this by factoring. We need two numbers that multiply to and add up to .
The pairs of factors of 28 are:
  • •1 and 28
  • •2 and 14
  • •4 and 7
Since the product is negative ( ), one factor must be positive and the other negative. Since the sum is negative ( ), the larger absolute value factor must be negative.
The pair and satisfies the conditions:
So, the quadratic equation factors as:
Step 4: Find the values of .
For the product of two factors to be zero, at least one of the factors must be zero:
Step 5: Verification (Optional).
Check :
LHS:
RHS:
LHS = RHS. So is a solution.
Check :
LHS:
RHS:
LHS = RHS. So is a solution.
The solutions are and .
The final answer is: