1)
x^2 - 49 = 0
factor
(x+7)(x-7) = 0
x+7 = 0; x = -7
x -7 = 0; x = 7
2)x^2 - 18x + 81 = 0
factor
(x- 9)(x - 9) = 0
x - 9=0; x = 9
3)
x^2 + 3x = 40
x^2+3x - 40 = 0
factor
(x + 8)(x - 5) = 0
x+8 = 0; x = -8
x -5 = 0; x = 5
4)
3x^2 - 75 = 0
3(x^2 - 25) = 0
3(x+5)(x-5) = 0
x + 5 = 0; x = -5
x - 5 = 0; x = 5
5)
2x^2 - 15 = 7x
2x^2 - 7x - 15 = 0
(2x + 3)(x - 5) = 0
2x+3 = 0; x = -3/2
x - 5= 0; x = 5
6)
4x^2 + 16x - 48 = 0
4(x^2 + 4x - 12) = 0
4(x + 6)(x - 2) = 0
x + 6 = 0; x = -6
x - 2 = 0 ; x = 2