90
obtain the expression for j + 3k then evaluate for x = 5
j + 3k = (x + 4)² + 3(8 - x) = (x + 4)² + 24 - 3x
(j + 3k)(5) = (5 + 4)² + 24 - (3 × 5) = 81 + 24 - 15 = 90
j(x) = (x + 4)² = x² + 8x + 16
+3k(x) = 3(8 - x) = 24 - 3x
(j + 3k)(x) = x² +5x + 40
(j + 3k)(5) = (5)² +5(5) + 40
= 25 + 25 + 40
= 90
Answer: 90
