Useing substitution/elimination method what is the solution set to x^2+y^2=25

4x-3y=0
a)(3,4) and (-3,-4)
b)(3,-4) and (-3,4)
c)(-4,3) and (4,-3)
d)(4,3) and (-4,-3)
PLEASE HELP!

There are two ways to do this.
(1) Try each of the multiple choices in the equations and see which one works, or
(2) Substitute 4x/3 for y in the first equation, making it an equation for x only. Solve that. With each of the x solutions you get, compute y.

Note that, since y = (4/3) x, x and y must have the same sign. This eliminates choices (b) and (c) right away. A bit more thought should help you eliminate (d) as an option.