Question

规定:a三角形b等于a加(a加1)加(a加2)加...加(a加b减1)

Answer 1

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