(2) Substitute x= 14 into (5x+22+15+12+19)/9.

(5x+22+ 15+ 12+ 19)/9

=(70+22+ 15+ 12+ 19)/9

= 138/9

y= 138/9

2. Substitute x=4 into 3a+x=a/2x+3.

Get 3a+4=a/8+3.

25/8a=- 1

a=-8/25

a-2a+3a-4a+5a...+99a- 100a

=-50a

Substitute a=-8/25 for -50a.

De -50a

=-50*-8/25

= 16

3.2x^2-6y^2+m(xy-9y^2)-(3x^2-3xy+7y^2)

=2x^2-6y^2+mxy-9my^2-3x^2+3xy-7y^2

=-x^2-( 13+9m)y^2+(m+3)xy

∫ There is no xy term in the above formula.

∴m+3=0

m=-3

Substitute m=-3 into-x 2-(13+9m) y 2+(m+3) xy to obtain.

-x^2-( 13+9m)y^2+(m+3)xy

=-x^2-( 13-27)y^2

=-x^2+ 14y^2