以下程序的功能是计算一元二次方程ax2+bx+c=0的根。请在【】内填入正确内容。#include ”stdio.h”#include ”math.h”main(){float a,b,c,t,disc,w,term1,term2;printf(”enter a,b,c:”);scanf(%f%f%f”,&a,&b,&c);if (【1】)if (【2】) printf(”no answer due to input error\n”);else printf(”the single root is %f\n”, - c/b);else{ disc=b*b-4*a*c;w=2*a;term1= -b/w;t=abs(disc);term2=sqrt(t)/w;if (【3】)printf(”complex root\n real part=%f imag part =%f\n”, term1,term2);elseprintf(”real roots\n root1=%f root2=%f\n”, term1+term2,term1-term2);}}
A speaker wants to demonstrate the change in world population since 1840. His clearest and most effective option for a visual aid to demonstrate this is a(n)______
A. Line graph.
B. Map.
C. Bar graph.
D. Chart.
Which form of presentation aids are drawings that outline and explain the parts of an object, process, or phenomenon that cannot be readily seen.
A. graphs
B. diagrams
C. objects
D. charts