Answer:
1a
Step-by-step explanation:
8000*0.25=2000
2000*0.25=500
500*0.25=125
...
By <em>direct</em> substitution and simplification, the <em>trigonometric</em> function z = cos (2 · x + 3 · y) represents a solution of the <em>partial differential</em> equation
.
<h3>How to analyze a differential equation</h3>
<em>Differential</em> equations are expressions that involve derivatives. In this question we must prove that a given expression is a solution of a <em>differential</em> equation, that is, substituting the variables and see if the equivalence is conserved.
If we know that
and
, then we conclude that:





By <em>direct</em> substitution and simplification, the <em>trigonometric</em> function z = cos (2 · x + 3 · y) represents a solution of the <em>partial differential</em> equation
.
To learn more on differential equations: brainly.com/question/14620493
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Answer:

Step-by-step explanation:

Answer:
A (-1,-10) ; A (-1,14)
Step-by-step explanation:

y^2 -4y - 140 = 0
Δ/4 = 4 + 140 = 144
y1 = 2 + 12 = 14
y2 = 2 -12= -10