42
Amaliy topshiriqlar
Darslik: 1-qism, 40-dars, 86–87-betlar
MaqsadNol bilan amallar; a − b − c = a − (b + c); masalani ikki usulda yechish.
Yangi so‘zlar
nol · zeroifoda · expressionikki usul · two wayseksponat · exhibit
Tushuntirish
Songa nol qo‘shsak yoki undan nol ayirsak, son o‘zgarmaydi: a + 0 = a, a − 0 = a. Sondan o‘zining o‘zini ayirsak, nol chiqadi: a − a = 0. Ketma-ket ayirish uchun: a − b − c = a − (b + c). Masalani ikki usulda yechsak, javob bir xil chiqishi kerak.
Namunalar
49 − 26 − 7 = 49 − (26 + 7) = 49 − 33 = 16.
18 + y = 18 → y = 0; 34 − m = 0 → m = 34.
Sinfda faoliyat
«Nol sehri»: bolalar nol bilan misollar tuzadi (a + 0, a − 0, a − a). Hamma misolni tenglamaga aylantirib, o‘z do‘stiga yechish uchun beradi.
Mashq
1
x − 25 = 25. x = ?
50
2
34 − m = 0. m = ?
34
3
31 − 12 − 15 = ?
4
4
Muzeyda 80 ta eksponat bor. Birinchi qavatda 30 ta, ikkinchi qavatda 25 ta. Uchinchi qavatda nechta eksponat bor?
25