4. Quyidagi yig‘indilarning qaysi birining javobi musbat yoki manfiy bo‘lishini aniqlang, so‘ng ularni kalkulyatorsiz hisoblang: a) (−8) + (+7); b) 25 + (−11); d) (−16) + 9; e) 0 + (−4).

a) Modullardan 8 kattaroq va u manfiy songa tegishli; demak, yig‘indi manfiy: (−8) + 7 = −(8 − 7) = −1.

b) 25 ning moduli 11 dan katta; demak, yig‘indi musbat: 25 + (−11) = 25 − 11 = 14.

d) 16 ning moduli 9 dan katta va manfiy songa tegishli; demak, yig‘indi manfiy: (−16) + 9 = −(16 − 9) = −7.

e) Nolga qo‘shilganda son o‘zgarmaydi: 0 + (−4) = −4, manfiy.

Javob: a) −1 (manfiy); b) 14 (musbat); d) −7 (manfiy); e) −4 (manfiy).