(2a-5)²+a(20-5a) при a= -2/5

Question

(2a-5)²+a(20-5a)
при a= -2/5

Answer 1

(2a-5)²+a(20-5a)=4a^2+25+20a-5a^2=-a^2+20a+25=5a(-a+9)
Т.к. а=-2/5, то
5*(-2/5)*(2/5+9)=-9,4