cac bai toan ve so hoc va hinh hoc

Neu keo dai day nho them 5 cm thi ditch cua hinh thang tang them la 40 cm2.

Cac bai toan ve so hoc va hinh hoc

Chuong I : so hoc

Bai 1:

a, 437 – 189 – 11

= 437 – (189 + 11)

= 437 – 200

= 237

b, (317 + 483) – 283

= 317 + (483 – 283)

= 317 + 200

= 517

c, 323 – (223 – 150)

= (323 + 223) + 150

= 100 + 150

= 250

d, 323 – (400 – 177)

= (323 + 177) – 400

= 500 - 400

= 100

Bai 2 :

a, 2 x 31 x 12 + 4 x 6 x 42 + 8 x 27 x 3

= 24 x 31 + 24 x 42 + 24 x 27

= 24 x (31 + 42 + 27)

= 24 x 100

= 2400

b, 36 x 28 + 36 x 82 + 64 x 69 + 64 x 41

= 36 x (28 + 82) + 64 x (69 + 41)

= 36 x 110 + 64 x 110

= 110 x (36 + 64)

= 110 x 100

= 11000

Bai 3 :

Tim 4 so tu nhien chan lien tiep co tong bang 5420

Bai lam

Ta co so do :

So 1 :

So thu 1 la : (5420 – 12) : 4 = 1352

So thu 2 la : 1352 + 2 = 1354

So thu 3 la : 1354 + 2 = 1356

So thu 4 la: 1356 + 2 = 1358

DS : So 1: 1352

So 2 : 1354

So 3: 1356

So 4 : 1358

Chuong 2: hinh hoc

Bai 1 : Hinh thang ABCD co day AB = 27 cm , day lon CD = 48cm Neu keo dai day nho them 5 cm thi ditch cua hinh thang tang them la 40 cm2 Tinh dien tich hinh thang ?

Bai lam

A 27cm B 5 40cm

D C

48cm

Bai lam

Chieu cao cua hinh thang ABCD la : 40 x 2 : 5 = 20 cm Dien tich hinh thang da cho la : (27 + 48) x 16 : 2 = 600 cm2

DS: 600cm2