Investment in research and development (R&D) can play a crucial role in a firm's growth. Through R&D, a firm can come up with more innovative solutions that help them produce goods and services more efficiently. This can lead to faster machines, increased productivity, and decreased production costs, resulting in decreased prices of products. As a result, the demand for the firm's products can increase, which can help the firm to grow in size.

Moreover, investment in R&D can lead to the creation of new products that were previously unavailable in the market. This can help the firm to diversify its product offerings, which can lead to larger exports and entry into new markets. Since there may be no direct competition initially, the firm can enjoy high demand and increase its market share, leading to higher profits and more reinvestment.

Another way in which investment in R&D can help a firm grow in size is by creating a bigger workforce. More skilled workers are required to carry out R&D activities, and this can lead to the creation of more job opportunities. This, in turn, can increase the size of the firm and provide it with a larger pool of resources to invest in future R&D.

Lastly, investment in R&D can provide firms with information on what products to produce, how to produce them, and how to market them. This information can help firms to make more informed decisions, thus increasing their chances of success. It can also influence what is produced in the future, which can lead to the creation of new industries and the growth of existing ones.

In conclusion, investment in research and development can help a firm grow in size by increasing innovation, creating new products, expanding into new markets, creating job opportunities, and providing information to make more informed decisions.