Answer: x = 4 , y = -3
Step-by-step explanation:
Going by the Cramer's rule , we first determine the determinant by dealing with only the coefficients of x and y in the 2 x 2 matrix.
2x - 3y = 17
5x + 4y = 8
2 -3
5 4, going by the rule now, we now have
(2 x 4) - (5 x -3)
8 + 15
= 23.
Now to find the value of x , replace the constants with the coefficient of x and divide by he determinants.
17 -3
8 4
---------------
2 -3
5 4
( 17 x 4 ) - ( 8 x -3 )
---------------------------
23
= 68 + 24
------------
23
= 92/23
= 4.
x = 4
Now to find y, just repeat the process by replacing the coefficient of y with the constants.
2 17
5 8
-----------
2 -3
5 4
( 2 x 8 ) - ( 5 x 17 )
-----------------------
23
16 - 85
---------
23
= -69/23
= -3
y = -3.
check
substitute for the values in any of the equations above.
2(4) - 3(-3)
8 + 9
= 17
The correct question is:
Determine whether the given function is a solution to the given differential equation. y = cosx + x^8; d²y/dx² + y = x^8 + 56x^6
Step-by-step explanation:
Given the differential equation
d²y/dx² + y = x^8 + 56x^6.
Suppose y = cosx + x^8 is a solution, then differentiating y twice, and adding it to itself, must give the value on the right hand side of the differential equation.
Let us differentiate y twice
y = cosx + x^8
dy/dx = -sinx + 8x^7
d²y/dx² = -cosx + 56x^6
Now,
d²y/dx² + y = -cosx + 56x^6 + cosx + x^8
= 56x^6 + x^8
Therefore,
d²y/dx² + y = x^8 + 56x^6
Which shows that y = cosx + x^8 is a solution to the differential equation.
It is 1/3 have a great day !!
