Percent - XYZ Custom Plus

362Chapter 5 Percent4. Find the value of the followingexpression when x is 10 andy is 4:​_3x + y3x − y ​Example 4Find the value of ​ 4x + ySolutiony with 2 to get_​when x is 5 and y is 2:4x − yThis time we have two different variables. We replace x with 5 and​_4(5) + 2 ​= ​20_ + 24(5) − 2 20 − 2 ​= ​ 22 _18 ​= ​ 11 _9 ​5. Find the value of(4x + 1)(4x − 1) when x is 2.Example 5Find the value of (2x + 3)(2x − 3) when x is 4.SolutionReplacing x with 4 in the expression, we have:(2 ⋅ 4 + 3)(2 ⋅ 4 − 3) = (8 + 3)(8 − 3)= (11)(5)= 556. Find the value of the followingexpression when x is 5.​_x3 + 8x + 2 ​Example 6Find the value of ​ x3 − 8Solution​ when x is 5:x − 2_We substitute 5 for x and then simplify:​_53 − 8​= ​125_ − 8​5 − 2 3= ​ 117 _3 ​= 39Answers4. ​_17 ​ 5. 63 6. 1913