Multiply the equation 2x+2y=8 by 3. Does the equation have the same solution set?
1 answer:
Multiply the equation:
The solution set is the same, because multiplying both sides of an equation by a non-zero number doesn't change the solution set. In fact, if you rewrite the equation as
Multiplying this by 3 (or whatever number, for all it matters) gives
Now, a product is zero if and only if at least one of the factor is zero. So, either or
Since the first is clearly impossible, the second one must be true, which is the original equation.
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via the angle sum formula of sin
which proves the second choice
the third choice is wrong since for x=0,y=0 it will show that 2=1 which is incorrect
for the fourth one you can do some thing similar to choice one just expand the sum formula of sin and that should be true too
so
the first , the second and the fourth are all true