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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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Answer:

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Step-by-step explanation:

Given:

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a = 2

Required:

Find b

Solution:

The question given suggests we are given measures for a ∆.

To find side b, which corresponds to angle B, first, we'd find angle A, which corresponds to side a, then apply the Law of sines to find side b.

=> A = 180 - (53 + 80) = 47°

Law of Sines: \frac{a}{sin(A} = \frac{b}{sin(B}

Plug in the values into the formula

\frac{2}{sin(47} = \frac{b}{sin(80}

Cross multiply

2*sin(80) = b*sin(47)

Divide both sides by sin(47) to make b the subject of formula

\frac{2*sin(80)}{sin(47} = b

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Answer:

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