Question

please answer my questions​

Answer 1

Answer:

 

Step-by-step explanation:

5.1 x 5.2 = (5+0.1)x(5+0.2)

formula used :- (x+a)(x+b)= x^2+(2ab)x+ab

 x = 5 ,

a=0.1,

b=0.2

= (5)^2 +(2x(0.1)x(0.2))5+(0.1)x(0.2)

= 25 +(0.04)5+0.02

=25+0.20+0.02

=25.22

so the requird answer is 25.22

13.  

(x+y)(2x+y)+(x-2y)(x-y)

=x(2x+y)+y(2x+y)+x(x-y)-2y(x-y)

= 2x^2+xy+2xy+y^2+x^2-yx -2xy +2y^2

= 2x^2+y^2+x^2+2y^2

3x^2+3y^2