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Find the value of integral(4 to 10) 2f(x)-3dx

Find the value of integral(4 to 10) 2f(x)-3dx-example-1

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We know that


\displaystyle \int_1^4 f(x) \, dx = 8


\displaystyle \int_1^(10) f(x) \, dx = 17

By linearity of the definite integral,


\displaystyle \int_4^(10) 2f(x) - 3 \, dx = 2 \int_4^(10) f(x) \, dx - 3 \int_4^(10) dx

Presumably, you're aware that


\displaystyle \int_a^b dx = b - a

for any two numbers a and b, so the last integral is simply 6.

From the known integrals, we also know


\displaystyle \int_1^(10) f(x) \, dx = \int_1^4 f(x) \, dx + \int_4^(10) f(x) \, dx


\displaystyle 17 = 8 + \int_4^(10) f(x) \, dx


\displaystyle \int_4^(10) f(x) \, dx = 9

so


\displaystyle \int_4^(10) 2f(x) - 3 \, dx = 2*9- 3*6 = \boxed{0}

User JHeth
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