Back in the long long ago you could roll out LAMP with a single yum command. In 2017, distro game has hardly kept up with the evolution in PHP and still comes with PHP 5.4 – to go to 7 in RHEL/CetOS 7 you have to do some surgery.
First remove all the php packages. Then let this rip.
yum install epel-release yum-utils
rpm -Uvh http://rpms.remirepo.net/enterprise/remi-release-7.rpm
yum-config-manager –enable remi-php71
yum install -y php71-php-pecl-memcached php71-php-mysql php71-php-xml php71-php-cli php
That’s all, just restart httpd and hack your /etc/php.ini (needs explicit definition for the time zone)