Question

решите уравнение
1) 81х^2-9=0
2) 16-4у^2=0
3) 16с^2-49=0
4) 64х^2-25=0

Answer 1

1) (9x-3)(9x+3)=0
9x=3 and  9x=-3
x=1/3  or  x=-1/3

2) (4-2y)(4+2y)=0
2y=4  2y=-4
y=2   y=-2

3)(4c-7)(4c+7)=0
4c=7  4c=-7
c=7/4  c=-7/4

4)(8x-5)(8x+5)=0
8x=5  8x=-5
x=5/8  x=-5/8