Ncert Solutions For Class 8 Maths Ex 9.1

Ncert Solutions For Class 8 Maths Chapter 9 Ex 9.1

Q.1. Identify the terms and their coefficients for each of the following expressions.

(I) 5abc2 – 3cb

Terms :  5abc2  

3cb

Coefficients: 5, -3

(II) 1+a+a2

Terms: 1, a, a2

Coefficients: 1, 1, 1

(III) 4x2y– 4 x2y2z+  z2

Terms: 4x2y2   ,  -4 x2y2z2    ,  Z2

Coefficient: 4,  -4,  1

(IV) 3 – xy + yz – zx

Terms:   3:  -xy,  yz,  -zx

Coefficient:  3:  -1,  1,  -1

(V) a2+b2ab

Terms: a2,  b2,  -ab

Coefficient: 12,  12,  -1

(VI)0.3x-0.6xy+0.5y

Terms: 0.3x,  -0.6xy,  0.5y

Coefficient: 0.3,  -0.6,  0.5

 

Q.2. Check whether the following polynomials are monomials, binomials or trinomials. Find out which polynomials do not fit any of these three categories?

1)  x+y,

2)  1000,

3)  x+x2+x3+x4,

4)  7+y+5x,

5)  2y3y2,

6)  2y3y2+4y3,

7)  5x-4y+3xy,

8)  4z15z2,

9)  ab+bc+cd+da,

10)  pqr,

11)  p2q+pq2,

12)  2p+2q,

Answer:

Monomials: 1000,   pqr

Binomials: x+y,   2y3y2,  4z15z2,   p2q+pq2,    2p+2q

Trinomials: 7+y+5x,    2y3y2+4y3,      5x-4y+3xy

Polynomials that do not fit any of these categories are :

x+x2+x3+x4, ab+bc+cd+da

 

Q.3.Add the following :

Note: The given expressions written in separate rows, with like terms one below the other and then the addition of these expressions are done.

(I)ab – bc,    bc – ca,    ca – ab

ab-bc

+   bc-ca

+  -ab+ca

=           0

(II) x – y+xy,       y-z+yz,        z-x+xz

x – y + xy

+      y -z+yz

+       -x+z +xz

=        xy+yz+xz

(III) 2a2b23ab+45+7ab3a2b2

2a2b23ab+4

+    3a2b2+7ab+5

a2b2+4ab+9

 

(IV) a2+b2b2+c2,c2+a2,2ab+2bc+2ca

a2+b2

+     b2+c2

+     c2+a2

+     2ab+2bc+2ca

=      2a2+2b2+2c2+2ab+2bc+2ca

 

Q.4. (i)Substract 4x-7xy+3y+12 from 12x-9xy+5y-3

Answer:

12x – 9xy + 5y –  3

4x – 7xy + 3y + 12

(-)     (+)    (-)    (-)

8x – 2xy + 2y – 15

(ii)Substract 3xy +5yz -7zx from 5xy-2yz-2zx+10xyz

5xy – 2yz -2zx +10xyz

3xy + 5yz -7zx

(-)      (-)      (+)

2xy-7yz + 5zx  +10xyz

(iii) Substract4p2q3pq+5pq28p+7q10from183p+11q+5pq2pq2+5p2q

183p11q+5pq2pq2+5p2q

 

108p+7q3pq+5pq2+4p2q

(+)          (+)   (-)  (+)   (-)            (-)

28+5p18q+8pq7pq2+p2q