Fundamental Theorem of Calculus Math Example 1

Follow the full solution, then compare it with the other examples linked below.

Example 1

easy
Let G(x)=โˆซ0x(t2+1)โ€‰dtG(x) = \int_0^x (t^2 + 1)\,dt. Find Gโ€ฒ(x)G'(x) using FTC Part 1.

Solution

  1. 1
    FTC Part 1 states: if G(x)=โˆซaxf(t)โ€‰dtG(x) = \int_a^x f(t)\,dt, then Gโ€ฒ(x)=f(x)G'(x) = f(x).
  2. 2
    Here f(t)=t2+1f(t) = t^2 + 1, so Gโ€ฒ(x)=f(x)=x2+1G'(x) = f(x) = x^2 + 1.
  3. 3
    No integration is needed โ€” the derivative of an integral with variable upper limit is just the integrand evaluated at xx.

Answer

Gโ€ฒ(x)=x2+1G'(x) = x^2 + 1
FTC Part 1 says differentiation undoes integration when the upper limit is the variable. You simply replace tt with xx in the integrand. This is the key link showing derivatives and integrals are inverse operations.

About Fundamental Theorem of Calculus

The theorem stating that differentiation and integration are inverse operations, linking antiderivatives to definite integrals.

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