Answer:
(A) Angles in equilateral triangle are congruent
Step-by-step explanation:
From the figure, it can be seen that in triangle ABD, which means that all the sides of the triangle are congruent and by the definition of equilateral triangle, ΔABD will be an equilateral triangle.
Therefore, Using the property that Angles in equilateral triangle are congruent, we can find the value of x.
Thus, option A is correct.
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Work Shown:
5x^3 + 14x^2 + 9x
x( 5x^2 + 14x + 9 )
To factor 5x^2 + 14x + 9, we could use the AC method and guess and check our way to getting the correct result.
A better way in my opinion is to solve 5x^2 + 14x + 9 = 0 through the quadratic formula
Then use those two solutions to find the factorization
x = -1 or x = -9/5
x+1 = 0 or 5x = -9
x+1 = 0 or 5x+9 = 0
(x+1)(5x+9) = 0
So we have shown that 5x^2 + 14x + 9 factors to (x+1)(5x+9)
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Overall,
5x^3 + 14x^2 + 9x
factors to
x(x+1)(5x+9)
