Question

Let f(x)=5x-4,g(x)=3x+7then find the value of k if (fog)(k)=7
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Answer 1

Step-by-step explanation:

(f o g)(x)

= f[g(x)]

= f(3x + 7)

= 5(3x + 7) - 4

= 15x + 31.

When (f o g)(k) = 7, 15k + 31 = 7.

=> 15k = -24, k = -8/5 = -1.6.