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coldgirl [10]
3 years ago
12

What is the value of the expression 2x2 + 3xy – 4y2 when x = 2 and y = - 4?

Mathematics
1 answer:
Bumek [7]3 years ago
5 0
Please use " ^ " to denote exponentiation:  <span>2x^2 + 3xy – 4y^2

Now let x=2 and y= -4:

2(2)^2 + 3(2)(-4) - 4(-4)^2 = 8 - 24 -4(16) = -16 - 4(16) = -5(16) = -80 (answer)</span>
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Your friend grace needs help to find the values of x,y and z in the figure below
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Answers:

x = 57

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=================================================

Work Shown:

x+123 = 180 .... since x and 123 form a straight line

x = 180-123

x = 57

y = 86 since the y and 86 angles are vertical angles

-------

For any triangle, the three angles always add to 180. So,

x+y+z = 180

57+86+z = 180

143+z = 180

z = 180-143

z = 37

As a check,

x+y+z = 57+86+37 = 180

which confirms the value of z

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4 years ago
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(The reason I did not do this by cross multiplying and dividing ratios is because it gives you the exact same answer if you are finding it per one, as I am here with per one minute. You can do it this way, it just wastes a bit of time.)

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