`3,`

`a,A = (x - 2)^2 - (x - 1)(x + 1) - x(1 - x)= (x² - 4x + 4) - (x^2 - 1) - (x - x²)= x² - 4x + 4 - x² + 1 - x + x²= x² - 5x + 5`

Thay `x=5`, có:

`x² - 5x + 5=5^2-5.5+5=25-25+5=5`

`b,B = - (2x - 1)²]^2 + (x + 1)² + (2x - 1)(2x + 1)= - (4x² - 4x + 1) + (x^2 + 2x + 1) + (4x² - 1)= -4x² + 4x - 1 + x^2 + 2x + 1 + 4x² - 1= x² + 6x - 1`

Thay `x=10`, có:

`B = x² + 6x - 1=10^2+6.10-1=100+60-1=41`

`c,C = (2x + 3)² - 2(2x + 3)(2x + 5) + (2x + 5)² + y= (4x^2 + 12x + 9) - 2(4x² + 16x + 15) + (4x² + 20x + 25) + y= 4x^2+ 12x + 9 - 8x² - 32x - 30 + 4x^2 + 20x + 25 + y= (4x² - 8x² + 4x²) + (12x - 32x + 20x) + (9 - 30 + 25) + y= 0 + 0 + 4 + y= y + 4`

Thay `x=2022,y=36`

`C = y + 4=36+4=40`

4,

`a,501^2= (500 + 1)² = 500² + 2*500*1 + 1² = 250000 + 1000 + 1 = 251001`

`b,502*498 = (500 + 2)(500 - 2) = 500² - 2² = 250000 - 4 = 249996`

`c,88^2+ 24*88 + 12² = (88 + 12)² = 100² = 10000`

`d,(437^2 - 363²) / (537^2 - 463²)= [(437 - 363)(437 + 363)] / [(537 - 463)(537 + 463)]= (74 × 800) / (74 × 1000) = 800 / 1000 = 4/5`

`@612009`