La fonction exponentielle

Propriétés algébriques de la fonction exponentielle - Exercice 1

25 min
40
Simplifier les expressions suivantes :
Question 1

a(x)=e3e4a\left(x\right)=e^{3} e^{4}

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
a(x)=e3e4a\left(x\right)=e^{3} e^{4} équivaut successivement à
a(x)=e3+4a\left(x\right)=e^{3+4}
a(x)=e7a\left(x\right)=e^{7}
Question 2

b(x)=e5e2b\left(x\right)=\frac{e^{-5} }{e^{2} }

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
b(x)=e5e2b\left(x\right)=\frac{e^{-5} }{e^{2} } équivaut successivement à
b(x)=e52b\left(x\right)=e^{-5-2}
b(x)=e7b\left(x\right)=e^{-7}
Question 3

c(x)=(e5)2e2e6c\left(x\right)=\frac{\left(e^{-5} \right)^{2} }{e^{2} e^{-6} }

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
c(x)=(e5)2e2e6c\left(x\right)=\frac{\left(e^{-5} \right)^{2} }{e^{2} e^{-6} } équivaut successivement à
c(x)=e5×2e2+(6)c\left(x\right)=\frac{e^{-5\times 2} }{e^{2+\left(-6\right)} }
c(x)=e10e4c\left(x\right)=\frac{e^{-10} }{e^{-4} }
c(x)=e10(4)c\left(x\right)=e^{-10-\left(-4\right)}
c(x)=e6c\left(x\right)=e^{-6}
Question 4

d(x)=e4(e5)2(e2)5e6d\left(x\right)=\frac{e^{-4} \left(e^{-5} \right)^{2} }{\left(e^{2} \right)^{5} e^{-6} }

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
d(x)=e4(e5)2(e2)5e6d\left(x\right)=\frac{e^{-4} \left(e^{-5} \right)^{2} }{\left(e^{2} \right)^{5} e^{-6} } équivaut successivement à
d(x)=e4e5×2e2×5e6d\left(x\right)=\frac{e^{-4} e^{-5\times 2} }{e^{2\times 5} e^{-6} }
d(x)=e4e10e10e6d\left(x\right)=\frac{e^{-4} e^{-10} }{e^{10} e^{-6} }
d(x)=e4+(10)e10+(6)d\left(x\right)=\frac{e^{-4+\left(-10\right)} }{e^{10+\left(-6\right)} }
d(x)=e14e4d\left(x\right)=\frac{e^{-14} }{e^{4} }
d(x)=e144d\left(x\right)=e^{-14-4}
d(x)=e18d\left(x\right)=e^{-18}
Question 5

f(x)=e2x+1e3x+5f\left(x\right)=e^{2x+1} e^{-3x+5}

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
f(x)=e2x+1e3x+5f\left(x\right)=e^{2x+1} e^{-3x+5} équivaut successivement à
f(x)=e2x+1+(3x+5)f\left(x\right)=e^{2x+1+\left(-3x+5\right)}
f(x)=ex+6f\left(x\right)=e^{-x+6}
Question 6

g(x)=ex+1e3x4g\left(x\right)=\frac{e^{-x+1} }{e^{3x-4} }

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
g(x)=ex+1e3x4g\left(x\right)=\frac{e^{-x+1} }{e^{3x-4} } équivaut successivement à
g(x)=ex+1(3x4)g\left(x\right)=e^{-x+1-\left(3x-4\right)}
g(x)=ex+13x+4g\left(x\right)=e^{-x+1-3x+4}
g(x)=e4x+5g\left(x\right)=e^{-4x+5}
Question 7

h(x)=(e3x+2)2h\left(x\right)=\left(e^{3x+2} \right)^{2}

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
h(x)=(e3x+2)2h\left(x\right)=\left(e^{3x+2} \right)^{2} équivaut successivement à
h(x)=e(3x+2)×2h\left(x\right)=e^{\left(3x+2\right)\times2}
h(x)=e3x×2+2×2h\left(x\right)=e^{3x\times 2+2\times 2}
h(x)=e6x+4h\left(x\right)=e^{6x+4}
Question 8

i(x)=e5x+7ex3e2x+3i\left(x\right)=\frac{e^{5x+7} e^{-x-3} }{e^{2x+3} }

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
i(x)=e5x+7ex3e2x+3i\left(x\right)=\frac{e^{5x+7} e^{-x-3} }{e^{2x+3} } équivaut successivement à
i(x)=e5x+7+(x3)e2x+3i\left(x\right)=\frac{e^{5x+7+\left(-x-3\right)} }{e^{2x+3} }
i(x)=e4x+4e2x+3i\left(x\right)=\frac{e^{4x+4} }{e^{2x+3} }
i(x)=e4x+4(2x+3)i\left(x\right)=e^{4x+4-\left(2x+3\right)}
i(x)=e4x+42x3i\left(x\right)=e^{4x+4-2x-3}
i(x)=e2x+1i\left(x\right)=e^{2x+1}
Question 9

j(x)=e2x+6(e4x+1)3ex+4j\left(x\right)=\frac{e^{-2x+6}\left(e^{4x+1} \right)^{3} }{e^{-x+4} }

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
j(x)=e2x+6(e4x+1)3ex+4j\left(x\right)=\frac{e^{-2x+6}\left(e^{4x+1} \right)^{3} }{e^{-x+4} } équivaut successivement à
j(x)=e2x+6×e(4x+1)×3ex+4j\left(x\right)=\frac{e^{-2x+6} \times e^{\left(4x+1\right)\times 3} }{e^{-x+4} }
j(x)=e2x+6×e4x×3+1×3ex+4j\left(x\right)=\frac{e^{-2x+6} \times e^{4x\times 3+1\times 3} }{e^{-x+4} }
j(x)=e2x+6e12x+3ex+4j\left(x\right)=\frac{e^{-2x+6} e^{12x+3} }{e^{-x+4} }
j(x)=e2x+6+12x+3ex+4j\left(x\right)=\frac{e^{-2x+6+12x+3} }{e^{-x+4} }
j(x)=e10x+9ex+4j\left(x\right)=\frac{e^{10x+9} }{e^{-x+4} }
j(x)=e10x+9(x+4)j\left(x\right)=e^{10x+9-\left(-x+4\right)}
j(x)=e10x+9+x4j\left(x\right)=e^{10x+9+x-4}
j(x)=e11x+5j\left(x\right)=e^{11x+5}
Question 10

k(x)=(e2x2xex+4)2k\left(x\right)=\left(\frac{e^{2x^{2} -x} }{e^{-x+4} } \right)^{2}

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
k(x)=(e2x2xex+4)2k\left(x\right)=\left(\frac{e^{2x^{2} -x} }{e^{-x+4} } \right)^{2} équivaut successivement à :
k(x)=(e2x2x)2(ex+4)2k\left(x\right)=\frac{\left(e^{2x^{2} -x} \right)^{2} }{\left(e^{-x+4} \right)^{2} }
k(x)=e(2x2x)×2e(x+4)×2k\left(x\right)=\frac{e^{\left(2x^{2} -x\right)\times2} }{e^{\left(-x+4\right)\times2} }
k(x)=e4x22xe2x+8k\left(x\right)=\frac{e^{4x^{2} -2x} }{e^{-2x+8} }
k(x)=e4x22x(2x+8)k\left(x\right)=e^{4x^{2} -2x-\left(-2x+8\right)}
k(x)=e4x22x+2x8k\left(x\right)=e^{4x^{2} -2x+2x-8}
k(x)=e4x28k\left(x\right)=e^{4x^{2} -8}
Question 11

l(x)=ex7e2x×e3x+5e2x+1l\left(x\right)=\frac{e^{x-7} }{e^{2x} } \times \frac{e^{3x+5} }{e^{-2x+1} }

Correction
  • eaeb=ea+be^{a} e^{b} =e^{a+b}
  • eaeb=eab\frac{e^{a} }{e^{b} } =e^{a-b}
  • (ea)b=ea×b\left(e^{a} \right)^{b} =e^{a\times b}
  • ea=1eae^{-a} =\frac{1}{e^{a} }
l(x)=ex7e2x×e3x+5e2x+1l\left(x\right)=\frac{e^{x-7} }{e^{2x} } \times \frac{e^{3x+5} }{e^{-2x+1} } équivaut successivement à :
l(x)=ex72x×e3x+5(2x+1)l\left(x\right)=e^{x-7-2x} \times e^{3x+5-\left(-2x+1\right)}
l(x)=ex72x×e3x+5+2x1l\left(x\right)=e^{x-7-2x} \times e^{3x+5+2x-1}
l(x)=ex7×e5x+4l\left(x\right)=e^{-x-7} \times e^{5x+4}
l(x)=ex7+5x+4l\left(x\right)=e^{-x-7+5x+4}
l(x)=e4x3l\left(x\right)=e^{4x-3}