Question

please answer it. it will be very thankful to you

Answer 1

I think it is right.

Answer 2

Hope u like my process
=====================
1)

$= > \bf \: (3ab - 2 {a}^{2} + 5 {b}^{2} )(2 {b}^{2} - 5ab + 3 {a}^{2} ) + (8 {a}^{3} b - 7 {b}^{4} ) \\ \\ = (5 {b}^{2} + 5ab - 2ab - 2 {a}^{2} )( 2{b}^{2} - 3ab - 2ab + 3 {a}^{2} ) + b( 8{a}^{3} - 7 {b}^{3} ) \\ \\ = (5b(b + a) - 2a(b + a))(b(2b - 3a) - a(2b - 3a)) + b(8 {a}^{3} - 7 {b}^{3} ) \\ \\ = (5b - 2a)(b + a)(b - a)(2b - 3a) + b(8 {a}^{3} - 7 {b}^{3} ) \\ \\ \bf \: since \: \: a = 1 \: \: and \: \: b = - 1 \: \: \\ \\ \bf \: = > b + a = - 1 + 1 = 0 \\ \\ = > 0 + ( - 1)(8 {( 1)}^{3} - 7( { - 1)}^{3} ) \\ \\ = - 1(8 - 7( - 1)) = - 1(8 + 7) \\ \\ \bf \: = - 15$
2)

$= > \bf \: (1.7x - 2.5y)(2y + 3x + 4) - 7.8 {x}^{2} - 10y \\ \\ \bf \: = > since \: \: x = 0 \: \: and \: \: y = 1 \\ \\ = > (1.7 \times (0) - 2.5 \times (1))(2 \times (1) + 3 \times (0) + 4) - 7.8 \times {(0)}^{2} - 10 \times (1) \\ \\ = ( - 2.5)(2 + 4) - 10 \\ \\ \: = - 2.5 \times (6) - 10 \\ \\ \bf \: = - 15 - 10 = - 25$
__________________________
Hope this is ur required answer

Proud to help you