Question

Dau coronita îmi trebuie urgent ex.21,23 și 40 de pe foaie

Answer 1

21.

a x a - a
5 x 5 - 5 = 25 - 5 = 20
6 x 6 - 6 = 36 - 6 = 30
7 x 7 - 7 = 49 - 7 = 42
8 x 8 - 8 = 64 - 8 = 56
9 x 9 - 9 = 81 - 9 = 72


23.

194 x 3 + 200 - a = 493
582 + 200 - a = 493
782 - a = 493
a = 782 - 493
a = 289

V: 194 x 3 + 200 - 289 = 493 ====== Adevarat


( 104 x 4 + 83 x 5 ) - a x 3 = 8 x 100 + 36 : 9
( 104 x 4 + 83 x 5 ) - a x 3 = 800 + 4
( 104 x 4 + 83 x 5 ) - a x 3 = 804
( 416 + 415 ) - a x 3 = 804
831 - a x 3 = 804
Notam cu x ( a x 3 )
831 - x = 804
x = 831 - 804
x = 27

a x 3 = x
a x 3 = 27
a = 27 : 3
a = 9

V: ( 104 x 4 + 83 x 5 ) - a x 3 = 8 x 100 + 36 : 9
( 416 + 415 ) - 9 x 3 = 804
831 - 9 x 3 = 804
831 - 27 = 804 ======= Adevarat




( 138 x 5 - 21 : 7 - 300 x 2 ) - 9 x 9 - r x 2 = 2
( 690 - 3 - 600 ) - 9 x 9 - r x 2 = 2
( 687 - 600 ) - 81 - r x 2 = 2
87 - 81 - r x 2 = 2
6 - r x 2 = 2
Notam cu x = r x 2
6 - x = 2
x = 6 - 2
x = 4

r x 2 = 4
r = 4 : 2
r = 2

V: ( 138 x 5 - 21 : 7 - 300 x 2 )- 9 x 9 - 2 x 2 = 2
( 690 - 3 - 600 ) - 81 - 2 x 2 = 2
( 687 - 600 ) - 81 - 4 = 2
87 - 81 - 4 = 2
6 - 4 = 2 ========= Adevarat




40 : 8 + 124 x 5 + i = 719
5 + 620 + i = 719
625 + i = 719
i = 719 - 625
i = 94

V: 40 : 8 + 124 x 5 + 94 = 719
5 + 620 + 94 = 719
625 + 94 = 719 ====== Adevarat



( 321 x 2 - 115 x 4 ) + 42 : i = 180 + 2 x 4
( 321 x 2 - 115 x 4 ) + 42 : i = 180 + 8
( 321 x 2 - 115 x 4 ) + 42 : i = 188
( 642 - 460 ) + 42 : i = 188
182 + 42 : i = 188
Notam cu x = 42 : i

182 + x = 188
x = 188 - 182
x = 6

42 : i = 6
i = 42 : 6
i = 7

V: ( 321 x 2 - 115 x 4 ) + 42 : 7 = 180 + 2 x 4
( 642 - 460 ) + 42 : 7 = 180 + 8
( 642 - 460 ) + 42 : 7 = 188
182 + 6 = 188 ======== Adevarat