Question

Bài 4: Tính bằng cách thuận tiện nhất: 
a)  7,25 x 0,34 + 2,75 x 0,34

b) 10,79 x 0,24 – 0,24 x 0,79 
c) 2,5 x 4 x 10 x 6,25 

Answer 1

\(\text{a) 7,25 x 0,34 + 2,75 x 0,34}\\ =0,34.\left(7,25+2,75\right)\\ =0,34.10\\ =3,4\)

Answer 2

\(\text{b) 10,79 x 0,24 – 0,24 x 0,79 }\\ =0,24.\left(10,79-0,79\right)\\ =0,24.10\\ =2,4\)

Answer 3

\(\text{c) 2,5 x 4 x 10 x 6,25 }\\ =\left(2,5.10.4\right).6,25\\ =100.6,25\\ =625\)

Answer 4

b, = 0,24.(10,79 -0,79)

= 0,24. 10

= 2,4

c, = (2,5.4).(10.6,25)

= 1. 62,5

=62,5

Answer 5

a) =0,34x(7,25+2,75)

=0,34x10

=3,4

b)=0,24x(10,79-0,79)

=0,24x10

=2,4

c)=(2,5x4)x(10x6,25)

=10x62,5

=625 

Answer 6

a) \(7,25\times0,34+2,75\times0,34\)
\(\Rightarrow0,34\times\left(7,25+2,75\right)\)
\(\Rightarrow0,34\times10\)
\(\Rightarrow3,4\)
b) \(10,79\times0,24-0,24\times0,79\)
\(\Rightarrow0,24\times\left(10,79-0,79\right)\)
\(\Rightarrow0,24\times10\)
\(\Rightarrow2,4\)
c) \(2,5\times4\times10\times6,25\)
\(\Rightarrow\left(2,5\times4\times10\right)\times6,25\)
\(\Rightarrow100\times6,25\)
\(\Rightarrow625\)

Answer 7

a) 7,25 x 0,34 + 2,75 x 0,34
= 0,34 x ( 7,25 + 2,75 )
= 0,34 x 10
= 3,4
b) 10, 79 x 0,24 - 0,24 x 0,79
= 0,24 x ( 10,79 - 0,79 )
= 0,24 x 10
= 2,4
c) 2,5 x 4 x 10 x 6,25
= ( 6,25 x 4 ) x ( 2,5 x 10 )
= 25 x 25
= 625