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if f(f(f(x)))=8x+21 find a+b
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- Let f(x)=ax+b
f(f(x))=a(ax+b)+b = a2x+ab+b
f(f(f(x)))= a(a2x+ab+b)+b =a3x+a2b+ab+b = 8x+21
so,on comparing
a3=8,it must be a=2
a2b+ab+b=21....b=3
a+b=5 - 12 years agoHelpfull: Yes(73) No(1)
- this ques is incomplete. f(x)=ax+b and if if f(f(f(x)))=8x+21 find a+b
Starting with , plug in for 'x' to get . Do so again to get . Now simplify to get . From here, just equate the two expressions and solve for 'a' and 'b'.
8x+21=a3+a2b+ab+b
a=2 and b=5
- 12 years agoHelpfull: Yes(5) No(7)
- ques is incomplete.its like f(x)=ax+b,correct ans a=2,b=3
- 12 years agoHelpfull: Yes(1) No(1)
- what are a & b ??
- 12 years agoHelpfull: Yes(0) No(0)
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