Answer:
The number is 4.
Step-by-step explanation:
We can answer the above question as follow:
The square of a number, x is written as: x²
Eight times the number is written as: 8x
From the question, we were told that the square of the number, x is 16 less than eight times the number. This can be written as:
x² = 8x – 16
Rearrange
x² – 8x + 16 = 0
Solving by factorisation method:
Multiply the 1st term (i.e x²) and the last term (i.e 16) together. The result is 16x² as shown below:
x² × 16 = 16x².
Next, find two factors of 16x² such that when we add them together, it will result to the 2nd term ( i.e – 8x).
The factors are –4x and –4x.
Next, replace – 8x in the equation with –4x and –4x. This is illustrated below:
x² – 8x + 16 = 0
x² – 4x – 4x + 16 = 0
Factorise
x(x – 4) – 4(x – 4) = 0
(x – 4)(x – 4) = 0
x – 4 = 0 or x – 4 = 0
x = 4 or x = 4
Thus, the number is 4.
***** Check *****
x² = 8x – 16
x = 4
4² = 8(4) – 16
16 = 32 – 16
16 = 16
