Simultaneous and quadratic equations?

(m-3)(m-4) = 20
m^2-7m+12=20
m^2-7m+12-20=0
m^2-7m-8=0
(m+1)(m-8)=0
m+1=0 m-8=0
m=-1 m=8 m={-1,8} answer//

x-2y=8
2x+7=1

2x+7=1
2x=1-7
2x=-6
x=-3 answer//

-3-2y=8
-2y=8+3
-2y=11
y=-11/2 answer//

(m-3)(m-4) = 20
m^2 - 3m - 4m + 12 = 20
m^2 - 7m + 12 - 20 = 0
m^2 - 7m - 8 = 0
m^2 - 8m + m - 8 = 0
m (m - 8) + 1 (m - 8) = 0
(m + 1) (m - 8) = 0
Either m + 1 = 0 or m - 8 = 0
m = -1 or m = 8



x - 2y = 8
2x + 7 = 1 --> 2x = 1 - 7 ---> 2x = -6 --->x = -3
Put x = - 3 in the other equation
x - 2y = 8
-3 - 2y = 8
- 2y = 8 + 3
- 2y = 11
y = -11/2
y = -5 1/2

1)
(m - 3)(m - 4) = 20
m*m - 3*m - m*4 + 3*4 = 20
m^2 - 3m - 4m + 12 - 20 = 0
m^2 - 7m - 8 = 0
m^2 + m - 8m - 8 = 0
(m^2 + m) - (8m - 8) = 0
m(m + 1) - 8(m - 1) = 0
(m - 1)(m - 8) = 0

m - 1 =0
m = 1

m - 8 = 0
m = 8

∴ m = 1 , 8

= = = = = = = =

2)
x - 2y = 8 (solve by using substitution)
2x + 7 = 1

2x + 7 = 1
2x = 1 - 7
x = -6/2
x = -3

x - 2y = 8
-3 - 2y = 8
2y = -3 - 8
y = -11/2 (-5.5)

∴ x = -3 , y = -11/2 (-5.5)

Question 1
m ² - 7m + 12 = 20
m² - 7m - 8 = 0
(m - 8)(m + 1) = 0
m = 8 , m = - 1

Question 2
AS GIVEN:-
2x = - 6
x = - 3

- 3 - 2y = 8
2y = - 11
y = - 11/2

x = - 3 , y = - 11/2