Given the joint variation and the constant of variation, the value of z when w = 11 and x = 7 is -22
z =( k × w) / x
where,
-42 = (k × 12) / 4
cross product
4 × -42 = 12k
-168 = 12k
k = -168 /12
k = -14
z =( k × w) / x
z = (-14 × 11) / 7
= -154 / 7
z = -22
Therefore, the value of z when w = 11 and x = 7 is -22
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