<p>已知等差数列<img src="https://file.gaojiufeng.cn/learnAppQuestion/cc/71/cc713929ff5372abf30d09b0f5acfc31.jpg" style="width: 100%;height: auto;">的首项与公差相等，<img src="https://file.gaojiufeng.cn/learnAppQuestion/cc/71/cc713929ff5372abf30d09b0f5acfc31.jpg" style="width: 100%;height: auto;">的前<img src="https://file.gaojiufeng.cn/learnAppQuestion/2e/78/2e78f7b6c4f0a547a620b878129fb456.jpg" style="width: 100%;height: auto;">项的和记作<img src="https://file.gaojiufeng.cn/learnAppQuestion/e7/83/e7837817e7cb4a59e4c9183a12448ca8.jpg" style="width: 100%;height: auto;">且<img src="https://file.gaojiufeng.cn/learnAppQuestion/ff/cb/ffcbf4b1b685d1cb4aba873e50c122b3.jpg" style="width: 100%;height: auto;">求数列<img src="https://file.gaojiufeng.cn/learnAppQuestion/cc/71/cc713929ff5372abf30d09b0f5acfc31.jpg" style="width: 100%;height: auto;">的首项<img src="https://file.gaojiufeng.cn/learnAppQuestion/b0/0c/b00c3e0ec625154255547e2fa510c3cc.jpg" style="width: 100%;height: auto;">及通项公式.</p>