Answer:
4x² + 29x + 7 = (4x + 1)(x + 7)
Explanation:
Simplify the polynomial:
Like terms are terms with same variable and same power.
 Perimeter = sum of all the sides
 = 3x² + 1 + 15x + 6 + x² + 14x
 = 3x² + x² + 15x + 14x + 1 + 6
Combine like terms,
 = 4x² + 29x + 7
Factorize:
 Sum = 29
 Product = 4*7 = 28
 Factors = 1 , 28 {28 + 1 = 29 & 28*1 = 28}
 Rewrite the middle term using the factors,
 = 4x² + x + 28x + 7
 = x(4x + 1) + 7(4x + 1)
 = (4x + 1)(x + 7)