I think is
x = 7 or x = -7
Equation at the end of step 1 : 3x2 - 147 = 0
Step 2 :Step 3 :Pulling out like terms :
3.1 Pull out like factors :
3x2 - 147 = 3 • (x2 - 49)
Trying to factor as a Difference of Squares :
3.2 Factoring: x2 - 49
Theory : A difference of two perfect squares, A2 - B2 can be factored into (A+B) • (A-B)
Proof : (A+B) • (A-B) =
A2 - AB + BA - B2 =
A2 - AB + AB - B2 =
A2 - B2
Note : AB = BA is the commutative property of multiplication.
Note : - AB + AB equals zero and is therefore eliminated from the expression.
Check : 49 is the square of 7
Check : x2 is the square of x1
Factorization is : (x + 7) • (x - 7)
Equation at the end of step 3 : 3 • (x + 7) • (x - 7) = 0
