Question

CAN U PLSS HELP ME I AM NOT ABLE TO SOLVE THIS QUESTION PLSS HELP ME
TOMORROW IS MY FIRST PAPER OF MATHS​

Answer 1

Step-by-step explanation:

2mn+3pm-5np _ (5mn-3np+7)

2mn+3pm-5np_5mn-3np+7

putting same terms together

=2mn-5mn+3pm-3pm-5np-3np+7

=-3mn-8np+7 is the answer

+3pm-3pm get cancelled

Answer 2

•Question 1:

Subtract 5mn-3np+7pm from 2mn+3pm-5np

Solution:

2mn+3pm-5np-(5mn-3np+7pm)

= 2mn+3pm-5np-5mn+3np-7pm

= 2mn-5mn+3pm-7pm-5np+3np

= -3mn-4pm-2np

= -(3mn+4pm+2np)

•Question 2:

Simplify: 3a(a²-a+2)-1, where a= -1/2

Solution:

$3a( {a}^{2} - a + 2) \\ = 3( - \frac{ 1}{2} )(( - { \frac{1}{2}) }^{2} - ( - \frac{1}{2} ) + 2) \\ = - \frac{ 3}{2} ( \frac{1}{4} + \frac{1}{2} + 2) \\ = - \frac{3}{2} ( \frac{1 + 2 + 8}{4} ) \\ = - \frac{3}{2} \times \frac{11}{4} \\ = - \frac{33}{8}$

•Question 3:

Find: (12.1)²-(7.9)² by using the identity.

Solution:

(12.1)²-(7.9)²

= (12.1+7.9)(12.1-7.9)

= 20×4.2

= 84

•Question 4:

Find the square by using suitable identity: (xy+3z)²

Solution:

(xy+3z)²

= (xy)²+(3z)²+2(xy)(3z) [(a+b)²=a²+b²+2ab]

= x²y²+9z²+6xyz

•Question 5:

Show that (4pq+3q)²-(4pq-3q)²= 48pq²

Solution:

L.H.S

(4pq+3q)²-(4pq-3q)²

= (4pq+3q+4pq-3q)(4pq+3q-4pq+3q) [a²-b²= (a+b)(a-b)]

= (8pq)(6q)

= 48pq² = R.H.S

Hence Proved.