To evaluate the definite integral ∫12(3x3+2x2−x+1)dx, we will first find the antiderivative of the function and then apply the Fundamental Theorem of Calculus.
Step 1: Find the indefinite integral of the function.
We use the power rule for integration, ∫xndx=n+1xn+1+C.
∫(3x3+2x2−x+1)dx=33+1x3+1+22+1x2+1−1+1x1+1+10+1x0+1+C
=34x4+23x3−2x2+x+C
Let F(x)=43x4+32x3−21x2+x.
Step 2: Evaluate the definite integral using the Fundamental Theorem of Calculus.
The definite integral is F(2)−F(1).
First, evaluate F(2):
F(2)=43(2)4+32(2)3−21(2)2+(2)
=43(16)+32(8)−21(4)+2
=3(4)+316−2+2
=12+316
To add these, find a common denominator:
=336+316=352
Next, evaluate F(1):
F(1)=43(1)4+32(1)3−21(1)2+(1)
=43(1)+32(1)−21(1)+1
=43+32−21+1
To add and subtract these fractions, find a common denominator, which is 12:
=4×33×3+3×42×4−2×61×6+1×121×12
=129+128−126+1212
=129+8−6+12=1217−6+12=1211+12=1223
Finally, calculate F(2)−F(1):
F(2)−F(1)=352−1223
To subtract these, find a common denominator, which is 12:
=3×452×4−1223
=12208−1223
=12208−23
=12185
The final answer is 12185.
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