f(x) = x² - 4x + 5
f(1 ) = 1² - 4 · 1 + 5
f(2) = 2² - 4 · 2 + 5
.................
f( 9 ) = 9² - 4 · 9 + 5
suma = ( 1² + 2² + .. + 9²) - 4 (1+2+..+ 9 ) + 5 · 9 =
= 9 · ( 9 + 1 ) ( 2·9 +1 ) / 6 - 4 ·9· ( 1 + 9) / 2 + 45 =
= 9 · 10 · 19 / 6 - 2·9 ·10 + 45 = 15 · 19 - 180 + 45 = 150