SAT Mathematics Practice Test 4

Since f(x)=

3

2

x+b and f(6)=7, substituting 6 for x in f(x)=

3

2

x+b gives f(6)

3

2

(6)+b=7. Then, solving the equation

3

2

(6)+b=7 for b gives

18

2

+b=7, or 9+b=7. Thus, b=7−9=−2. Substituting this value back into the original function gives f(x)=

3

2

x−2; therefore, one can evaluate f(−2) by substituting −2 for x:

3

2

(−2)−2=−

6

2

−2=−3−2=−5
Choice B is incorrect as it is the value of b, not of f(−2). Choice C is incorrect as it is the value of f(2), not of f(−2). Choice D is incorrect as it is the value of f(6), not of f(−2).