Answer: X= -1 OR X= 11
Step-by-step explanation:
Step 1 : Equate ( x-5)² since it occurred twice, hence the reason 2 is added in front of (x-5)²
= (x-5)²
= (x-5)(x-5)
= (x²-5x-5x+25)
= (x²-10x+25)
Step 2: multiply the result by two since it occurs twice and also bring the equation
= 2 (x²-10x+25) +7 = 79
= 2x²- 20x+50+7 = 79
= 2x²- 20x+57 =79
Step 3: most quadratic equation are always equal to zero, let's make this one equal to Zero by subtracting 79 from both sides
= 2x²-20x+57-79 = 79-79
= 2x²-20x-22=0
Step 4: divide the equation by a common number to get the least coefficient of the three coefficients
Dividing the three by 2
(2x²-20x-22)/2 = x²- 10x- 11
Step 5: Factorise completely
Sub step 1 : the first term in the equation is X² which makes the first term coefficient 1; the second term in the equation is -10x which makes the second term coefficient -10, the constant has a coefficient of -11
Sub step 2: multiply the coefficient of the first term (1) and the constant (-11) which gives us (-11)
1*-11 = -11
Sub step 3: Get two numbers in such a way that the addition of the first number and the second number gives the second coefficient in the quadratic equation and the multiplication of the two numbers will give us the product of the first coefficient and the constant.
And the two numbers is +1 and -11, the sum of the two numbers will give us -10 and the product will give us -11.
Step 6: slot the two numbers (+1, -11) into the equation by making themr replace the second coefficient
x²-10x-11=0
= x²+x-11x-11 =0
Step 7: split the equation into two and Factorise further
= (x²+x)(-11x-11) =0
= x(x+1)-11(x+1) = 0
= x+1= 0 or x-11 =0
Step 8 split them into individual equation
= x+1= 0.
Subtract 1 from both sides
= X+1-1=0-1
= x= -1
Or X should be
= x-11=0
Add 11 to both sides
= X-11+11 = 0+11
= x= 11
