Answer:
x = 14
y = -7
z = -3
but this is none of the provided answer options !
Step-by-step explanation:
it's really easy by principle. it's just some work to do.
we try to find equations to express one variable in terms of the others.
but one thing there is : your teacher made a mistake.
the right solution is x = 14, y = -7, z = -3
your teacher made a typo at d.
but the right answer should be d.
just to give you an idea how this can be done (and also to prove that there is a mistake by the teacher):
we can directly try to transform one expression into one that describes x by y and z.
and then another to describe e.g. z by y. and then solve the third one just for y. and then we get the other 2 by these other expressions.
or we can e.g. add or subtract one equation to/from another. this is one of these cases, because we can find really simple expressions that way :
we do
5x + 6y + 7z = 7
- (3x + 4y + 3z = 5)
- (2x + 2y + 3z = 5)
---------------------------
0x + 0y + z = -3
=> z = -3
3x + 4y - 3×3 = 5
3x = -4y + 14
x = (-4y + 14)/3
2×(-4y + 14)/3 + 2y - 9 = 5
(-8y + 28)/3 + 2y = 14
-8y + 28 + 6y = 42
-2y = 14
y = -7
x = (-4×-7 + 14)/3 = (28+14)/3 = 42/3 = 14
Answer:
F = -16
Step-by-step explanation:
F/4-5=-9
Add 5 to each side
F/4-5+5=-9+5
F/4=-4
Multiply each side by 4
F/4 *4=-4*4
F = -16
Step-by-step explanation:
the option with the isoceles triangles can NOT be just of that proof, because nowhere is it defined or proven that there is or are isoceles triangles involved. even though the picture looks like it, but that does not mean anything for the formal proof.
actually, this proof is the same (and is also valid) for non-isoceles triangles.
-8/10,-12/15,-16/20,-20/25,-24/30,etc.
