f(x) continues in [a,b] interval,and differentiable (a,b) b>a>0
alpha differs 0
proove that there is b>c>a

in that formula:
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my trial:
i mark alpha as "&"
mean theorim says f'(c)=[(f(b)-f(a)]/(b-a)

[f(b)*(a^&) - f(a)*b^&] / [a^& - b^&]= f(c) -c * [(f(b)-f(a)]/[(b-a) * &]


using mean theorem i replaced f'(c)
what should i do next??