The completely factored form of the quadratic expression 4x^2 + 12x - 72 is (x + 6) * 4(x - 3).
To completely factor the quadratic expression 4x^2 + 12x - 72, we can follow these steps:
Step 1: Find the product of the coefficient of the quadratic term (4) and the constant term (-72). In this case, the product is -288.
Step 2: Look for two numbers whose product is the same as the result obtained in Step 1 (-288) and whose sum is equal to the coefficient of the linear term (12). In this case, the numbers are 24 and -12.
Step 3: Rewrite the middle term (12x) using the two numbers found in Step 2:
4x^2 + 24x - 12x - 72
Step 4: Group the terms:
(4x^2 + 24x) - (12x + 72)
Step 5: Factor out the greatest common factor from each group:
4x(x + 6) - 12(x + 6)
Step 6: Notice that we have a common factor of (x + 6) in both terms. Factor it out:
(x + 6)(4x - 12)
Step 7: Simplify further by factoring out 4 from the second term:
(x + 6) * 4(x - 3)
The completely factored form of the quadratic expression 4x^2 + 12x - 72 is (x + 6) * 4(x - 3).