新手甲：
對(duì)不起,確實(shí)寫(xiě)錯(cuò)了.應(yīng)為C=-(A*B).謝謝大家!現(xiàn)重新上傳.[圖片]500){this.resized=true;this.width=500;this.alt='這是一張縮略圖，點(diǎn)擊可放大。\n按住CTRL，滾動(dòng)鼠標(biāo)滾輪可自由縮放';this.style.cursor='hand'}"onclick="if(!this.resized){returntrue;}else{window.open('http://u.dianyuan.com/bbs/u/37/1136776745.gif');}"onmousewheel="returnimgzoom(this);">