X+3y=7
x-3y=1
add them together
x+3y=7
<u>x-3y=1 +
</u>2x+0y=8
2x=8
divide 2
x=4
subsitute
x+3y=7
4+3y=7
subtract 4
3y=3
divid 3
y=1
x=4
y=1
answer is A
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A parabola with an equation, y2 = 4ax has its vertex at the origin and opens to the right.
It's not just the '4' that is important, it's '4a' that matters.
This type of parabola has a directrix at x = -a, and a focus at (a, 0). By writing the equation as it is, the position of the directrix and focus are readily identifiable.
For example, y2 = 2.4x doesn't say a great deal. Re-writing the equation of the parabola as y2 = 4*(0.6)x tells us immediately that the directrix is at x = -0.6 and the focus is at (0.6, 0)
Given the equation: (km / 3) - 2x = 4, it is essential to isolate x to obtain the expression to solve it. This is done below:
(km / 3<span>) - 2x = 4
</span>
Adding 2x to both sides:
(km / 3<span>) - 2x + 2x = 4 + 2x
</span>(km / 3<span>) = 4 + 2x
</span>
Subtracting 4 from both sides:
(km / 3<span>) - 4 = 4 + 2x - 4
</span>(km / 3<span>) - 4 = 2x
</span>
Dividing 2 from both sides:
[(km / 3<span>) - 4] /2 = 2x /2
</span>[(km / 3<span>) - 4] /2 = x
</span>x = (km / 6) - 2
Just like simplifying any other fraction.
Divide the top number and bottom number
by their greatest common factor.
The greatest common factor of 40 and 2 is 2 .
