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Elis [28]
3 years ago
13

If x + y = 7 and xy = 4, then find the value of x^2 + y^2.

Mathematics
2 answers:
Evgen [1.6K]3 years ago
6 0
X+y=7
xy=4

in xy=4, divide both sides by any variable (lets say i divide it y y)
xy=4
x=4/y
Now substitute it to the 1st equation
x+y=7
4/y+y=7
Multiply both sides by y
4+y^2=7y
Change to standard form
y^2-7y=4
Use the square of something...
y^2-7y+49/4=4+49/4
(y+7/2)^2=65/4
Squareroot both sides
y+7/2=posinega(sqrt of 65)/2
y=(sqrt of 65)/2-7/2
or y=-(sqrt of 65)/2-7/2
babunello [35]3 years ago
3 0

I don't know really how to do this stuff but I have learned in 7th grade and still working on it.

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hammer [34]
Wait is the middle school.
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Which best explains how you know that P(2, 7) is on the same line as Q(7, 4) and R(12, 1)?
Helen [10]

Answer:

See explanation below

Step-by-step explanation:

The best explanation is noticing that in order to get from the point R (12, 1) to the point Q (7, 4) we move 5 units to the left and 3 units up. And to go from point Q (7, 4) to point P (2, 7) we do exactly the same: move 5 units to the left and 3 units up. That means that these points are all connected via the same rate of change:  - 3/5, which is in fact the slope of the line the three points belong to.

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Nezavi [6.7K]

Answer:

its correct bro ;) click next

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3 years ago
Variable y varies directly with variable x, and y = 5 when x = 8.
qaws [65]
Y = kx

Plug in what we know:

5 = k(8)

5 = 8k

Divide 8 to both sides:

k = 0.625

Plug this back into the equation along with y = 15:

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Divide 0.625 to both sides:

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4 0
3 years ago
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vova2212 [387]

Answer:

I'm sorry but what is the question?

Step-by-step explanation:

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