Answer :
[tex]f(g(x))=3(2x+a)^2-7\\\\
3(2\cdot0+a)^2-7=68\\
3(2+a)^2=75\\
(a+2)^2=25\\
a+2=5 \vee a+2=-5\\
a=3 \vee a=-7[/tex]
The value of a is equal to +5 and -5.
What is an expression?
Expression in maths is defined as the collection of the numbers variables and functions by using signs like addition, subtraction, multiplication, and division.
The value of a is calculated as:-
3x² - 7 = 68
3 ( 2x + a)² -7 = 68
Put x = 0
3 ( a ) ² = 75
a ² = 75 / 3
a = √25
a = ±5
Therefore, the value of a is equal to +5 and -5.
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