Answer:
make Y the subject in eqn........ 1
y + 7 = 2x
y = 2x - 7...........eqn 3
put y = 2x - 7 into eqn 2
x² - xy + 3y² = 15
x² - x(2x - 7) + 3(2x - 7)(2x - 7) = 15
x² - 2x² + 7x + 3(4x² + 14x -14x + 21) = 15
x² - 2x² + 7x + 12x² + 42x - 42x + 63 = 15
x² - 2x² + 7x + 12x² + 63 = 15
x² - 2x² + 12x² + 7x + 63 = 15
11x² + 7x + 63 - 15 = 0
11x² + 7x + 48 = 0
11x² + 7x = - 48
11x²/11 + 7x/11 = - 48/11
x² + 7x
Answer:
8/17
Step-by-step explanation:
The correct and complete question is:
<em>Use △XYZ, in which ∠X is a right angle and tanY=8/15. What is the ratio for sinY?</em>
From definition:
tan(Y) = opposite/adjacent
From the graph and the question:
tan(Y) = XZ/XY = 8/15
Then:
XZ = 8 and XY = 15. Using pytaghorean theorem:
XZ² + XY² = YZ²
8² + 15² = YZ²
√289 = YZ
17 = YZ
From definition:
sin(Y) = opposite/hypotenuse
From the graph:
sin(Y) = XZ/YZ
sin(Y)= 8/17
The given equations satisfy the given conditions. There are
2 equations and 2 unknowns, so a certain solution can be found.
This can be solved using substitution,
Substituting eqn 2 to eqn 1:
2(2y – 10) + 3y =1240
Simplifying,
y = 180
x = 350
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