Question

A = x2- 4 tại x = 102

 

Answer 1

A=x²-4=(x-2)(x+2)

Khi x=102 thì \(A=\left(102-2\right)\left(102+2\right)\)

\(=104\cdot100=10400\)

Answer 2

\(A=x^2-4\)

\(A=x^2-2^2\)

\(A=\left(x-2\right)\left(x+2\right)\)

Thay \(x=102\) vào A ta được:

\(A=\left(102-2\right)\left(102+2\right)\)

\(A=100.104\)
\(A=10400\)