z varies directly with x and inversely with y^2. When x = 2 and y = 5, z = 8. What is the value of z when x = 4 and y = 9?
2 answers:
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Answer:
x = 2 , y = 0 , z = 3
Step-by-step explanation:
Cramer's rule is a rule through which we can find the solution of linear equation.
we have the three linear equations as
x+2y+3z=11
2x+y+2z=10
3x+2y+z=9
AX=B
A: coefficient matrix
X= unknown vectors(x,y,z)
D = values of the linear equation (11 , 10 , 9)
now we find the determinant of the given linear equation
determinant of the matrix will be
A = = 1(1-4) - 2(2-6) + 3(4 - 3)
= 1(-3) - 2(-4) + 3(1)
= -3+8+3 = 8
also D
so the determinant is Non zero we can apply Cramer's rule
we will be replacing the first column of the coefficient matrix A with the values of D
by replacing the first column we will get the value of the variable 'x'
Dx = = 11(1-4) -2(10-18) + 3(20-9) = -33+16+33 = 16
x = =
= 2
similarly
Dy = = 1(10-18) -11(2-6) + 3(18 -30) = -8 +44 -36 = 0
y = = 0
Dz= = 1(9 - 20) -2(18 - 30) + 11(4 -3) = -11 +24 +11 = 24
z = =
so we have the solution as
x = 2 , y = 0 , z = 3
Therefore the solution for the given linear equations is (2,0,3).