Identities- STD 8

Self Evaluation/Assessment Questions

Question : 1 : (1 Mark )

Fill the blank box

i(r+u)= ir+

Question : 2 (1 Mark )

Fill the blank box

c(s-w)= cs-

Question : 3 (5 Mark )

Using the Identity

a(b+c)=ab+ac

Calculate


     8 X 47


8x47 = 8X( 40+ )


= 8 x 40 + 8 x


= +


=

Question : 4 (5 Mark )

Using the Identity

a(b-c)=ab-ac

Calculate


     5 X 17


5x17 = 5X( 20- )


= 5 x 20 - 5 x


= -


=

Question : 5 (1 Mark )

Using the Identity

(a+b)(c+d)=ac+ad+bc+bd


Fill the blank box




(e+i)(l+y) =

Question : 6 (11 Mark )

Using the Identity

(a+b)(c+d)=ac+ad+bc+bd


Calculate


     47 X 24


47 = 40+


24 = 20+


∴ 47 X 24=( + ) ( + )

= + + +


=

Question : 7 (9 Mark )

Using the Identity

(a+b)²=a²+2ab+b²

Calculate

     74²

74²=( 70+ )²


= ² + 2x x + ²


= + +


=

Question : 8 (9 Mark )

Using the Identity

(a-b)²=a²-2ab+b²

Calculate

     67²

67²=( 70- )²


= ² - 2x x + ²


= - +


=

Question : 9 (11 Mark )

Using the Identity

     (a+b)(a-b)

Calculate

     13 x 7

13 = 10 +


7 = 10 -


∴ 13 x 7 =

( + ) ( - )

= ² - ²

= -

=

Question : 10 (4 Mark )