1) (х+7)(7-х)=49-x^2 2)(4b+1)(1-4b)=1-16b^2 3)(5m+2)(2-5m)=4-25m^2
1) (х+7)(7-х)=(7+x)(7-x)=49-x² 2)(4b+1)(1-4b)=1-16b² 3)(5m+2)(2-5m)=4-25m²