a△b=a+(a+1)+(a+2)+...+(a+b-1)
1.求1三角形100的值.
1△100
=1+(1+1)+(1+2)+...+(1+100-1)
=1+2+3+...+100
=5050
2.已知x三角形10等于75,求x
x△10
=x+(x+1)+(x+2)+...+(x+10-1)
=10x+45
则,10x+45 =75
解得x=3