解答


(ア)4  (イ)-7 (ウ)(-19/20) (エ)7ab (オ)(5/6) (カ)(5R5) (キ)8x+1


解説

(カ)(10/R5)+R45=(10R5/5)+3R5=2R5+3R5=(2+3)R5=5R5

(キ)(x+1)^2-x(x-6)=x^2+2x+1-x^2+6x=2x+1+6x=8x+1